Detection  f/  t/p^  Co;imN 
Food  Adulterants, 


Edwin  A-Bruce 


Revised  Edition 


Digitized  by  tine  Internet  Arcliive 

in  2007  witln  funding  from 

IVIicrosoft  Corporation 


littp://www.arcliive.org/details/detectionofcommoOObruGiala 


|Detection  of  the  Common 
Food  Adulterants/ 


BY 

EDWIN  M.  RRUCE 

PROFESSOR  OF  CHEMISTRY,  HEAD  OF  DEPARTMENT 
INDIANA  STATE  NORMAL  SCHOOL 


THIRD    EDITION 

REVISED    AND    ENLARGED 


k-' 


NEW  YORK 
D.  VAN  NOSTRAND  COMPANY 

2S  Park  Place 
1917 


Copyright,  1907,  1917 
By  D.  Van  Nostrand  Company 


The  Plimpton  Press  Norwood  Mass.  UJSA. 


PREFACE   TO  THE  THIRD   EDITION 

It  is  very  gratifying  to  all  who  have  been  engaged  in 
the  crusade  against  the  adulteration  of  foods,  which  was 
so  prevalent  a  few  years  ago,  to  mark  the  great  success 
which  has  been  attained.  No  small  part  of  the  success 
has  been  due  to  the  chemical  examination  of  the  foods. 
Health  officers,  chemistry  teachers  and  pupils,  those  in 
domestic  science  and  the  homes  themselves,  throughout 
the  country  are  becoming  more  or  less  proficient  in  the 
simple  qualitative  tests  which  reveal  the  true  quality  of 
the  various  food  products.  With  this  host  of  inspectors 
it  is  hoped  that  the  poisoning  of  foods  will  be  only  a 
matter  of  memory. 

This  book  has  been  revised  so  that  it  contains  the 
latest  and  best  tests  for  the  common  food  adulterants. 
The  author  wishes  to  take  this  opportunity  to  express 
his  thanks  to  the  various  Clubs  which  have  indorsed  the 
book,  hoping  this  revised  form  will  still  meet  their  ap- 
proval. 

Terre  Haute,  Ind. 
Sept.  29,  1917. 


PREFACE  TO  FIRST  EDITION 

Because  of  the  recent  agitation  of  the  pure  food  ques- 
tion throughout  the  country,  health  officers,  food-inspectors, 
and  chemistry  teachers  and  students  are  constantly  called 
upon  to  test  the  purity  of  various  foods.  And  this  usually 
involves  nothing  more  than  making  simple  qualitative  tests 
for  adulterants.  In  view  of  the  fact  that  there  is  now  no 
text  or  manual  devoted  exclusively  to  the  qualitative  exam- 
ination of  foods,  this  litde  book  is  ofTered  to  those  who  are 
interested  in  this  work. 

Its  aim  is  to  bring  together  in  one  small  book  the  best  and 
simplest  qualitative  tests  for  all  the  common  food  adulter- 
ants. It  contains  a  brief  statement  of  the  adulterants 
likely  to  be  found  and  the  reason  for  their  use.  It  is  hoped 
that  it  will  be  specially  valuable  to  chemistry  teachers  in 
furnishing  excellent  supplementary  work  in  qualitative 
analysis.  But  it  is  hoped  that  it  will  find  its  greatest  use- 
fulness in  contributing  something  toward  the  great  pure 
food  reform. 

It  is  impossible  to  make  due  mention  of  all  the  sources 
from  which  these  various  tests  have  been  collected,  but 
where  possible,  the  author's  name  has  been  associated  with 
the  test. 

Terre  Haute,  Ind. 
March  25,  1907. 


TABLE  OF   CONTENTS 

CHAPTER   I 

Dairy  Products i 

Milk  —  Purity  of  milk,  dirt,  hair,  etc.  —  Adultera- 
tions of  —  Coloring  matters  —  Annatto  —  Caramel  — 
Coal-tar  colors  —  Preservatives  —  Formaldehyde  — 
Boric  acid  —  Salicylic  acid  —  Gelatin  —  Starch. 

Butter  —  Adulterations  of  —  Coloring  matter  — 
Preparation   of   sample  —  Annatto  —  Coal-tar   colors 

—  Saffron  —  Turmeric  —  Marigold  —  Process  or  reno- 
vated butter  —  Oleomargarine  —  Cottonseed  oil. 

CHAPTER  II 
Meat  and  Eggs lo 

Adulterations  of  —  Fresh  and  smoked  —  Preserva- 
tives —  Potassium  nitrate  —  Boric  acid  —  Sulfurous 
acid  —  Salicylic  add  —  Benzoic  acid  —  Canned  — 
Preservatives  (same  as  those  of  fresh  and  smoked 
meat)  —  Heavy  metals  —  Coloring  matter  (see  under 
sausages,  etc.)  —  Fish,  salt,  dried  and  oysters  — ■ 
Preservatives  —  Boric  acid  (same  under  smoked  and 
fresh  meat)  —  Coloring  matter  —  Aniline  red  and 
cochineal-carmine  —  In  sausages,  chopped  meat, 
preparations  and  corned  meat  —  Starch  —  In  sau- 
sages, deviled  meat  and  similar  products  —  Diseased 
meats  —  Horse-flesh  in  sausages  and  in  mince-meat. 

Eggs  —  Test  for  age. 

CHAPTER  III 

Ceseal  Products i8 

Flour  —  Adulteration  of  —  Alum  —  Copper  sulfate 

—  Substituted  flours  —  General  test  —  Corn  meal  in 
wheat  flour  —  Wheat  flour  in  rye  flour  —  Ergot  in  rye 
flour. 

Bread  —  Adxilterations    of  —  Alum  —  Copper    sul- 
fate. 
Ginger  Cake  —  Adulterations  of  — .  Stannous  chlorid. 


vi  CONTENTS 

CHAPTER  IV  PAGE 

Leavening  Materials 22 

Baking  Powders  —  Flour  or  starch  —  Adultera- 
tions of  —  Tartaric  acid  (free  or  combined)  —  Tartaric 
acid  (free)  —  Phosphoric  acid  —  Sulfates  (calcium, 
etc.)  —  Gypsum  —  Ammonium  salts  —  Alum. 

Cream  of  Tartar  —  Adulterations  of  —  Tartaric  acid 
(free  or  combined)  —  Aluminium  salts  —  Ammonia  — 
Calcium  phosphate  —  Earthy  materials  —  Lime. 

CHAPTER  V 

Canned  and  Bottled  Vegetables 27 

Adulterations  of  —  Preservatives  —  Preparation  of 
sample  —  Formaldehyde  —  Sulfurous  acid  and  the 
sulfites  -r-  Salicylic    acid  —  Saccharin  —  Benzoic    acid 

—  Coloring  matter  —  Cochineal  —  Coal-tar  dyes  — 
Copper  salts  —  In  green  pickles,  beans,  peas,  etc.  — 
Turmeric  —  In  mixed  pickles  —  Heavy  metals  (other 
than  copper,  same  as  under  meats)  —  Soaked  vege- 
tables —  Peas,  beans  and  corn  —  Alum  —  In  pickles 

—  Examination  of  the  can  or  box. 

CHAPTER  VI 

Fruits  and  Fruit  Products 36 

Adulterations  of  —  Preservatives  —  Preparation  of 
sample  —  Salicylic    acid  —  Benzoic   acid  —  Saccharin 

—  Coloring  matter  —  Coal-tar  dyes  —  Cochineal  — 
Acid  magenta  —  Apple  juice  in  jellies  made  from  small 
fruits  —  Detection  (see  test  for  starch)  —  Starch  — 
In  jellies,  jams  and  such  products  —  Gelatin  —  In 
jellies  —  Agar  agar  —  Heavy  metals  —  Arsenic. 

CHAPTER   VII 

Flavoring  Extracts 45 

Lemon  Extract  —  Lemon  oil  —  Citral  —  Oil  of 
citronella  —  Tartaric  or  citric  acid  —  Methyl  alcohol 

—  Coloring  matter  —  Turmeric  —  Coal-tar  colors. 
Vanilla    Extract  —  Adulterations    of  —  Preliminary 

test  —  Alkali  —  Foreign    resins  —  Caramel  —  Tannin 

—  Coumarin. 


CONTENTS  vii 

CHAPTER  VIII  PAGE 

Saccharine  Products 52 

Honey  —  Adulterations  of  —  General  observations 
—  Cane  sugar  —  Commercial  glucose  syrup  —  Gelatin. 
Maple  Syrup  —  Adulterations  of  —  General  exami- 
nation —  Glucose. 

CHAPTER   IX 

Spices 54 

Mustard  —  Adulterations  of  —  Flour  —  Coloring 
matter  —  Turmeric  —  Martius  yellow  or  analogous 
coal-tar  coloring  matter  —  Cayenne  pepper. 

Pepper  —  Adulterations  of  —  General  test  — 
Ground  olive  stones  —  Cayenne  pepper. 

CHAPTER  X 

Vinegar 58 

Adulterations  of  —  Preparation  of  sample  — 
General  observations  —  Cider  vinegar  —  Free  mineral 
acids  —  General  tests  —  Sulfuric  acid  —  Hydrochloric 
add  (free)  —  Malic  acid  —  Coloring  matter  —  Cara- 
mel —  Coal-tar  colors  —  In  wine  vinegar  —  Free  tar- 
taric acid  —  In  wine  vinegar. 

CHAPTER  XI 

Fats  and  Oils 64 

Lard  —  Adulterations  of  —  Cottonseed  oil  —  Cot- 
tonseed stearin  —  Beef  stearin. 

Olive  Oil  —  Adulterations  of  —  General  test  —  Cot- 
tonseed oil  —  Peanut  oil  —  Sesame  oil  —  Rape  oil. 

CHAPTER  XII 

Beverages 69 

Coffee  —  Adulterations  of  —  General  test  —  Color- 
ing matter  —  Imitation  coffee  beans  —  Chicory. 

Tea  —  Adulterations  of  —  Foreign  leaves  —  Ex- 
hausted tea  leaves  —  Lie  tea  —  Facing  —  Catechu. 


PURE  FOOD  TESTS 

CHAPTER  I 
DAIRY  PRODUCTS 

MILK 

Milk  is  adulterated  by  watering,  removing  the  cream  or 
by  adding  some  foreign  substance.  Formaldehyde,  boric 
acid  or  salicyUc  acid  may  be  added  to  preserve  the  milk. 
Annatto,  caramel  or  some  coal-tar  dye  is  added,  sometimes 
to  improve  the  color  of  the  milk,  and  at  other  times  to  cover 
up  traces  of  watering.  Gelatin  and  starch  are  added  for 
the  same  purpose,  though  they  are  not  frequently  used. 
Baking  soda  is  sometimes  used  to  neutraUze  the  acid 
formed  in  the  milk. 

Purity  of  Milk 

Only  lactic  acid  bacteria  should  be  present  in  normal 
milk  and  these  produce  neither  gas  nor  bad  odors.  The 
presence  of  foreign  bacteria  may  be  determined  by  the 
so-called  Wisconsin  curd  test.  Heat  a  pint  of  the  milk 
in  a  covered  jar  or  bottle  to  about  98°  F.  Coagulate  the 
milk  by  adding  10  drops  of  standard  rennet  extract  and 
thoroughly  mixing.  Remove  the  whey.  Its  removal 
may  be  facilitated  by  cutting  the  curd  up  into  small  pieces 
with  a  knife.  Drain  off  the  whey  completely  until  the 
curd  is  well  matted.  Immerse  the  vessel  containing  the 
curd  in  warm  water,  98°  to  102°  F.,  and  incubate.    Keep 


2  PURE  FOOD  TESTS 

the  vessel  closed  to  retain  any  odors.  After  6  to  9  hours 
open  and  observe  the  odor;  and  by  cutting  with  a  sharp 
knife  ascertain  if  it  is  full  of  pin  holes  or  gas  holes.  Again 
note  the  odor.  When  this  curd  is  spongy  it  indicates  the 
presence  of  gas-forming  bacteria  and  hence  bad  milk. 
Bad  odors  indicate  the  same  quality  of  milk. 

Dirt,  Hair,  etc. 

Insert  a  plug  of  clean  absorbent  cotton  in  the  mouth 
of  a  funnel  from  the  inside.  Filter  through  this  a  pint  of 
the  well  mixed  milk.  Examine  the  sediment  collected 
by  the  aid  of  a  magnifying  glass. 

ARTIFICIAL  COLORliSTG  MATTER 

Annatto 

Add  acid  sodium  carbonate  to  a  sample  of  the  milk 
until  it  shows  a  shght  alkaUne  reaction.  Immerse  a 
piece  of  filter-paper  and  leave  it  in  for  12  or  15  hours.  If 
annatto  is  present,  there  will  be  a  reddish-yellow  stain  on 
the  paper. 

Caramel 

Leaches  Method.  —  Warm  150  cc.  of  the  sample  and  add 
5  cc.  of  acetic  acid,  then  continue  heating  it  nearly  to  the 
boiling  point,  stirring  while  it  is  being  heated.  Separate 
the  curd  by  gathering  it  with  the  stirring  rod  or  by  pouring 
through  a  sieve.  Press  out  all  the  whey  from  the  curd  and 
macerate  the  latter  for  several  hours  (10  to  12  hours)  in 
50  cc.  of  ether.  It  is  best  to  do  this  in  a  tightly  corked 
flask,  shaking  it  frequently.    If  the  milk  was  uncolored  or 


DAIRY  PRODUCTS  3 

colored  with  annatto  the  curd  when  thus  treated  will  be 
white.  If  the  curd  is  a  dull  brown  color  caramel  was  prob- 
ably used  to  color  the  milk.  Confirm  its  presence  by  shak- 
ing a  portion  of  the  curd  with  concentrated  hydrochloric 
acid  (sp.  gr.  1.20)  and  gently  heating.  If  the  acid  solution 
turns  blue  while  the  curd  does  not  change  its  color,  caramel 
was  used  to  color  the  milk.  (Remember  Ifcat  the  ether- 
extracted  curd  must  be  brown.) 

Coal-tar  Colors 

Lythgoe's  Method.  —  Mix  in  a  porcelain  vessel  about 
15  cc.  each  of  the  sample  of  milk  and  hydrochloric  acid 
(sp.  gr.  1.20)  and  break  up  the  curd  into  coarse  lumps  by 
shaking  gently.  If  an  azo-color  was  used  to  color  the  milk 
this  curd  will  be  pink,  but  the  curd  of  normal  milk  will  be 
white  or  yellowish. 

Starch 

The  presence  of  starch  in  milk  may  be  detected  by 
heating  a  small  quantity  of  the  milk  to  boiling.  When 
it  has  cooled  add  a  drop  of  iodin  in  potassium  iodid,  and 
if  starch  is  present  there  will  be  a  blue  coloration. 

Gelatin 

A .  W.  Stokes'  Method.  —  Dissolve  i  part  by  weight  of 
mercury  in  2  parts  of  nitric  acid  (sp.  gr.  1.42).  Add  24 
times  this  volume  of  water.  Mix  equal  volumes  (about 
10  cc.)  of  this  reagent  and  the  milk  or  cream,  shake  well 
and  add  20  cc.  of  water.  Shake  again  and,  after  standing 
5  minutes,  filter.  When  a  great  quantity  of  gelatin  is  pres- 
ent the  filtrate  will  be  opalescent  instead  of  perfectly  clear. 


4  PURE  FOOD  TESTS 

To  a  little  of  this  filtrate  in  a  test  tube  add  the  same  volume 
of  a  saturated  aqueous  solution  of  picric  acid.  If  much 
gelatin  is  present  a  yellow  precipitate  is  produced,  smaller 
amounts  produce  a  cloudiness.  If  the  filtrate  is  perfectly 
clear  gelatin  is  absent  and  picric  acid  may  be  added  without 
producing  any  noticeable  effect. 

PRESERVATIVES 
Formaldehyde 

Hehner's  Sulfuric  Acid  Test.  —  Put  lo  cc.  of  the  sus- 
pected milk  in  a  wide  test  tube  and  pour  carefully  down 
the  side  of  the  inclined  tube  about  5  cc.  commercial  sul- 
furic acid  so  that  it  forms  a  separate  layer  at  the  bottom. 
A  violet  coloration  at  the  union  of  the  two  liquids  indicates 
the  presence  of  formaldehyde.  If  the  commercial  acid  is 
not  available,  the  pure  acid  may  be  used,  but  a  few  drops 
of  ferric  chlorid  must  be  added.  Sometimes  the  charring 
effect  of  the  acid  makes  it  advisable  to  use  the  following 
test: 

Hydrochloric  Acid  Test.  —  2  cc.  of  10  per  cent  ferric 
chlorid  is  added  to  one  Liter  of  commercial  hydrochloric 
acid  sp.  gr.  i.  2  (or  any  quantity  in  this  proportion).  To 
10  cc.  of  this  mixture  add  lo  cc.  of  the  milk  to  be  tested. 
Heat  the  mixture  slowly  nearly  to  the  boiUng  point,  in  an 
evaporating  dish,  but  agitating  it  all  the  while  to  prevent 
the  curd  collecting  in  one  mass.  If  formaldehyde  is  pres- 
ent there  will  be  a  violet  coloration.  It  is  said  that  by 
this  test  as  small  a  quantity  of  formaldehyde  as  i  part  in 
250,000  parts  of  milk  can  be  detected.  It  is  not  so 
sensitive  in  sour  milk. 


DAIRY  PRODUCTS 


Boric  Acid 


Turmeric  Paper  Test.  —  Incinerate  some  of  the  milk, 
and  acidulate  the  ash  with  a  very  few  drops  of  dilute  hydro- 
chloric acid  and  afterwards  dissolve  it  in  a  few  drops  of 
water.  Place  a  strip  of  turmeric  paper  in  this  solution  for 
a  few  minutes,  then  remove  and  dry  it.  If  boric  acid  either 
free  or  combined  is  present,  the  turmeric  paper  will  be 
turned  to  a  cherry-red  color. 

Another  way  of  making  this  test.  —  U.  S.  Dep.  of  Agr., 
Div.  of  Chem.,  Bui.  65,  p.  no:  Make  strongly  alkahne 
with  lime  water,  25  grams  of  the  milk,  and  evaporate  to 
dryness  on  the  water  bath.  Destroy  the  organic  matter 
by  igniting  the  residue.  Dilute  with  15  cc.  of  water  and 
acidify  with  hydrochloric  acid.  Then  add  i  cc.  of  the 
concentrated  acid.  Dip  a  piece  of  deUcate  turmeric  paper 
in  the  solution;  and  if  borax  or  boric  acid  is  present,  it 
will  have  a  characteristic  red  color  when  dry.  Ammonia 
changes  it  to  a  dark  blue  green,  but  the  acid  will  restore 
the  color. 

(Turmeric  paper  may  be  prepared  by  dipping  pieces  of 
smooth,  thin  filter  paper  in  a  solution  of  powdered  turmeric 
in  alcohol.) 

Salicylic  Acid 

(This  is  not  often  used  as  a  preservative  of  milk.) 
Leach  suggests  the  following  method  for  its  detection.  — 
Dissolve  one  gram  of  mercury  in  2  grams  of  nitric  acid 
(sp.  gr.  1.42)  and  then  add  to  the  solution  the  same  volume 
of  water.  Add  i  cc.  of  this  reagent  to  50  cc.  of  the  milk 
to  be  tested,  and  shake  and  filter.    The  perfectly  clear 


6  PURE  FOOD  TESTS 

filtrate  is  shaken  with  ether  and  the  ether  extract  evap- 
orated to  dryness.  Then  add  a  drop  of  ferric  chlorid 
solution,  and  a  violet  color  will  be  produced  if  salicylic 
acid  is  present. 

BUTTER 

Butter  is  often  colored  with  annatto,  saffron,  turmeric, 
marigold  or  coal-tar  colors.  By  a  certain  process,  stale  or 
old  butter  is  sometimes  worked  over  and  made  to  appear 
fresh  for  a  time.  This  is  sold  under  the  name  of  ''  process  " 
or  "renovated"  butter.  Foreign  fats  like  cottonseed  oil, 
sesame  oil,  or  oleomargarine  may  be  substituted  for  or 
added  to  pure  butter. 

COLORING  MATTER 

Martinis  Test.  —  Add  2  parts  of  carbon  bisulfid,  a  little 
at  a  time  and  with  frequent  shaking,  to  15  parts  of  alcohol. 
Shake  25  cc.  of  this  solution  with  5  grams  of  the  butter, 
and  let  stand  for  some  time.  The  carbon  bisulfid  dissolves 
out  the  fatty  matter  and  settles  to  the  bottom.  The 
alcohol  remains  on  top  and  will  dissolve  out  any  artificial 
colors  that  may  be  present.  If  only  a  little  coloring  matter 
is  present  use  more  of  the  butter. 

Annatto 

Evaporate  a  portion  of  the  extract  to  dryness  and  add 
sulfuric  acid  to  the  residue.  If  annatto  is  present  a  green- 
ish-blue color  forms.  Should  a  pink  tint  result  the 
presence  of  a  coal-tar  color  is  to  be  suspected. 


DAIRY  PRODUCTS  7 

Coal-tar  Colors 

These  colors  will  dye  wool  or  silk  if  pieces  of  the  fiber  are 
boiled  in  the  diluted  alcoholic  extract,  which  has  first  been 
acidified  with  hydrochloric  acid.  The  normal  butter  color- 
ing matter  will  not  dissolve  when  thus  treated. 

Geisler's  Method.  —  To  a  few  drops  of  the  clarified  fat  on 
a  porcelain  surface,  add  a  very  little  fuller's  earth.  If  a 
pink  to  violet-red  coloration  is  produced  in  a  short  time 
the  presence  of  an  azo-color  is  indicated. 

Saffron 

When  saffron  is  present,  nitric  acid  colors  the  alcoholic 
extract  green,  and  hydrochloric  acid  colors  it  red. 

Turmeric 

Add  ammonia  to  the  alcoholic  extract,  and  if  it  turns 
brown  it  indicates  the  presence  of  turmeric. 

Marigold 

Add  silver  nitrate  to  the  extract,  and  if  it  turns  black 
the  presence  of  marigold  is  indicated. 

Process  or  Renovated  Butter 

Heat  a  little  of  the  suspected  butter  in  a  spoon  or  dish, 
and  if  it  is  process  butter  it  will  sputter,  but  not  foam 
much.  Make  the  test  also  with  some  butter  known  to  be 
pure  and  fresh. 

Hess  and  Doolittle  Test.  —  Melt  some  of  the  butter  (say 


8  PURE  FOOD  TESTS 

40  grams)  at  about  50°  C.  If  the  butter  is  pure  and  fresh 
the  melted  fat  will  clear  up  almost  as  soon  as  it  is  melted, 
while  the  fat  of  process  butter  remains  turbid  for  quite 
a  while.  After  most  of  the  curd  has  settled,  decant  as 
much  as  possible  of  the  fat.  Pour  the  remainder  on  a 
wet  filter.  Add  a  few  drops  of  acetic  acid  to  the  water 
that  runs  through  from  the  filter,  and  boil.  If  it  was 
ordinary  butter  this  filtrate  will  become  milky,  but  if 
process  butter  a  flocculent  precipitate  will  form. 


Oleomargarine 

Immerse  a  test  tube  containing  some  of  the  filtered  fat 
in  boiling  water  for  2  minutes.  Make  a  mixture  of  i  part 
glacial  acetic  acid,  6  parts  ether,  and  4  parts  alcohol. 
Add  to  20  cc.  of  this  mixture  in  a  50  cc.  test  tube,  i  cc.  of 
the  heated  fat,  which  may  be  transferred  by  means  of  a  hot 
pipette.  Stopper  the  tube  and  shake  it  well.  Immerse 
in  water  at  15°  or  16°  C.  Pure  butter  when  thus  treated 
remains  clear  for  quite  a  while.  There  will  be  only  a  very 
little  deposit  after  standing  an  hour,  but  oleomargarine 
gives  a  deposit  almost  immediately,  and  in  a  few  minutes 
there  will  be  a  copious  precipitate. 

When  the  oleomargarine  in  butter  is  in  about  the  pro- 
portion of  I  :io,  it  will  not  separate  much  short  of  15 
minutes. 

"Milk"  Test.  — Add  a  spoonful  of  butter  to  60  cc.  of 
sweet  milk  in  a  wide-mouth  bottle  setting  in  boiling  water. 
Stir  until  the  fat  is  melted.  Then  place  the  bottle  in 
ice  water  and  stir  the  fat  till  it  solidifies.  Either  fresh  or 
renovated  butter  will  solidify  in  a  granular  mass  distributed 


DAIRY  PRODUCTS  g 

throughout  the  milk  in  finely  divided  particles.  Oleo- 
margarine will  solidify  in  one  chunk  which  may  be  lifted 
out  with  the  stirrer. 

Cottonseed  Oil 

The  presence  of  this  oil  may  be  detected  by  Halpen's 
test,  which  is  given  under  lard,  page  64. 


CHAPTER  II 

^  MEATS  AND   EGGS 

Meats  are  preserved  by  treating  them  with  jMDtassium 
nitrate,  boric  acid,  sulfurous  acid,  salicylic  acid,  or  benzoic 
acid.  Cheap  meat  may  be  substituted  for  the  more  ex- 
pensive. A  few  cases  of  horse  meat  in  mince  meat  and 
sausages  have  been  discovered.  Diseased  and  stale  meats 
have  been  found  on  the  market.  Canned  meats  often  con- 
tain zinc,  tin,  and  lead,  and  sometimes  even  arsenic.  Ani- 
line-red or  cochineal-carmine  may  be  added  to  improve  the 
color  of  chopped  or  ground  meats.  Starch  is  sometimes 
added  to  sausage  and  similar  meat.  Fish  and  oysters  may 
be  preserved  with  boric  acid  or  borax. 

FRESH  AND   SMOKED   PRODUCTS  —  PRESERV- 
ATIVES 

Potassium  Nitrate  (Saltpeter) 

Corned  and  smoked  meats  are  usually  preserved  with 
saltpeter.  Since  smoked  and  cured  meats  are  used  in 
making  potted  meats,  saltpeter  is  quite  frequently  found  in 
the  latter.  It  may  be  detected  by  the  usual  test  for  nitrates 
since  no  other  nitrate  is  apt  to  be  present,  though  one  may 
identify  the  metal  by  the  qualitative  test  for  potassium. 

To  test  for  nitrates  treat  a  little  of  the  meat  with  2  or  3  cc. 
of  a  I  per  cent  solution  of  diphenylamine  in  strong  sulfuric 


MEATS  II 

acid.  If  a  nitrate  is  present  a  deep  blue  color  forms  in- 
stantly, which  is  not  obscured  by  the  charring  effect  of  the 
acid. 

Boric  Acid 

Pick  apart  into  fine  pieces  about  25  or  50  grams  of  the 
lean  meat  and  warm  with  a  little  water  which  has  a  few  drops 
of  hydrochloric  acid  in  it.  Soak  a  piece  of  turmeric  paper 
in  the  extract,  and  if  boric  acid  is  present  the  paper  will  be 
colored  rose -red  when  it  is  dry.  A  weak  alkali  turns  this 
colored  paper  olive. 

Another  method  is  to  burn  a  piece  of  the  meat  to  an  ash, 
after  being  treated  with  lime  water.  Make  a  solution  of 
the  ash  and  make  slightly  acid  with  hydrochloric  acid. 
Then  test  with  the  turmeric  paper  with  the  same  results  as 
in  the  above  method. 

SuLFUROUS  Actd 

U.  S.  Dep.  Agr.,  Bureau  Chem.,  Bui.  107,  pp.  113,  187: 

Digest  40  or  50  grams  of  the  meat  in  hot  water,  treat  with 
10  cc.  glacial  phosphoric  acid  to  coagulate  the  proteids. 
Strain  through  a  cotton  bag  and  transfer  the  filtrate  to  a 
short-necked  flask  and  distil  receiving  the  first  part  of  the 
distillate  in  a  solution  of  iodin.  Boil,  and  add  barium 
chloride.  If  sulfurous  acid  is  present,  it  will  be  oxidized 
to  sulfuric  acid  and  precipitated  as  barium  sulfate  by  the 
barium  chlorid.  More  than  a  mere  trace  of  the  precipitate 
proves  that  some  sulfite  was  used  to  preserve  the  meat. 

Another  method  suggested  by  Kammerer  is  to  place  the 
meat  on  paper,  which  has  been  saturated  with  potassium 
iodate  moistened  with  dilute  sulfuric  acid  (1:8);  nitric  oxid 
must  not  be  present.     If  sulfurous  acid  is  present  a  deep 


12  PURE  FOOD  TESTS 

blue  color  forms  at  once.  A  trace  of  this  color  may  form 
after  some  time  with  meat  that  is  not  fresh,  hence  this 
method  cannot  be  used  in  examining  canned  meat. 

Salicylic  Acid 

Heat  50  grams  of  the  meat  in  50  cc.  of  water.  Add  10  cc. 
of  a  strong  solution  of  glacial  phosphoric  acid  and  strain 
through  a  cotton  bag.  Extract  the  filtrate  with  a  little 
ether  (about  50  cc.)  in  a  separatory  funnel.  Let  the  ether 
evaporate  spontaneously.  Take  up  the  residue  with  3  cc. 
of  water,  and  add  one  or  two  drops  of  a  one-half  per  cent 
solution  of  ferric  chlorid.  If  salicylic  acid  is  present  the 
mixture  will  be  purple  or  violet. 

Leach  makes  the  same  test  by  slightly  acidifying  a  por- 
tion of  the  lean  meat,  then  extracting  with  ether,  and  evap- 
porating  to  dryness  and  testing  the  residue  with  a  drop  of 
ferric  chlorid  solution.  A  deep  violet  coloration  is  pro- 
duced if  salicylic  acid  is  present. 

Benzoic  Acid 

Mohlefs  Method.  —  Prepare  a  sample  as  in  the  test  for 
salicylic  acid  by  heating  50  grams  of  the  meat  in  50  cc.  of 
water.  Add  10  cc.  of  a  concentrated  solution  of  glacial 
phosphoric  acid,  and  strain  through  a  cotton  bag.  Neu- 
tralize with  sodium  hydrate  and  evaporate  to  dryness  or  to 
a  small  volume.  After  treating  with  3  cc.  of  concentrated 
sulfuric  acid,  heat  till  white  fumes  appear.  Add  4  or  5  crys- 
tals of  potassium  nitrate  and  continue  heating  until  the  solu- 
tion is  colorless  or  nearly  so.  When  cool  dilute  with  water, 
add  an  excess  of  ammonia,  and  place  in  a  narrow  vessel  like 
a  test  tube.  Add  one  or  two  drops  of  ammonivun  sulfid 
carefully  so  that  the  liquids  do  not  mix.     If  the  surface  of 


MEATS  13 

the  liquid  immediately  becomes  red,  benzoic  acid  is 
present. 

If  this  test  is  not  carefully  performed,  it  is  worthless,  as 
other  substances  give  similar  results. 

Confirm  its  presence  by  neutralizing  the  aqueous  solution 
of  the  extracted  benzoic  acid  with  sodium  hydroxid;  con- 
centrate to  a  very  small  volume.  Acidify  with  sulfuric 
acid.  A  white  flocculent  precipitate  shows  the  presence  of 
considerable  benzoic  acid. 

CANNED  MEAT 

If  in  preparing  canned  meat  only  fresh  meat  is  used,  there 
is  little  need  for  the  use  of  preservatives,  but  as  considerable 
smoked  and  cured  meat  is  thus  used,  preservatives  may 
find  their  way  into  canned  meat. 

The  same  preservatives  should  be  looked  for  as  in  fresh 
and  smoked  meat  and  the  same  test  made  for  each. 

Heavy  Metals 

A.  H.  Allen's  Method.  —  About  25  grams  of  the  substance 
is  mixed  slowly  with  enough  strong,  pure  sulfuric  acid  to 
just  moisten  the  mass,  avoiding  an  excess.  Heat  on  a 
water-bath  for  a  short  time,  then  raise  the  temperature 
gradually,  and  maintain  till  the  chlorids  seem  to  be  decom- 
posed. It  must  not  be  hot  enough,  however,  to  volatilize 
the  sulfuric  acid.  Then  add  i  cc.  of  strong  nitric  acid  and 
heat  till  red  fumes  are  given  off.  Freshly  ignited  magnesia 
in  the  proportion  of  0.5  gram  for  each  cc.  of  sulfuric  and 
nitric  acid  previously  used  is  now  stirred  into  the  mass  and 
the  whole  ignited  at  a  dull  red  heat.  This  is  best  done  in  a 
gas-muffle.  When  cool,  moisten  the  ash  with  nitric  acid 
and  gently  re-ignite,  repeating  this  treatment  till  the  carbon 


14 


PURE  FOOD   TESTS 


Is  entirely  consumed.  Treat  the  residue  with  8  or  lo  drops 
of  strong  sulfuric  acid,  heat  till  fumes  are  given  ofiF,  cool, 
boil  with  water,  dilute  to  about  loo  cc.  and  saturate  with 
hydrogen  sulfid,  filter,  examine  as  follows: 


Zinc   and    iron  may  be 
in  solution.    Add  bromine 
water  to  destroy  hydrogen 
sulfid    and    to   oxidize  the 
iron,    boil    and    add     am- 
monium hydrate  in  excess, 
boil  again  and  filter. 

Lead,   tin,   copper,  and   calcium,  if 
present,  will  be  in  the  precipitate  and 
residue.     Fuse  the  mass  in  a  porcelain 
crucible  for  at  least  ten  minutes  with 
2  grams  each  of  potassium  and  sodium 
carbonates    and   half  as  much   sulfur. 
After  cooling,  boil  with  water  and  filter. 

The   precipi- 
tate will  contain 
the  iron  and  the 
phosphates. 

Filtrate,  when 
blue,  proves  the 
presence   of 
nickel. 

Residue.     Add  hydrochlo- 
ric acid  and  boil  as  long  as 
hydrogen  sulfid  is  given  off. 
A     few    drops    of    bromine 
water  will  complete  the  oxi- 
dation of  the   copper  sulfid. 
Filter,    and   add  ammoniimi 
hydroxid  in  excess  to  the  fil- 
trate.     When  the  filtrate  is 
blue,  it    indicates  the    pres- 
ence of  copper.     Acidify  the 
filtrate    with  acetic  acid  and 
test  for   lead  by  adding  po- 
tassium   chromate,   a   yellow 
precipitate       being      formed 
when  it  is  present. 

The     filtrate 
may  contaip  tin. 
Acidify      with 
acetic  acid,  and 
if  tin  is  present 
a     yellow     pre- 
cipitate of  stan- 
nic   sulfid    will 
form. 

I.    Heat   to 
boiling  and  add 
potassium    fer- 
roc  yanid.  A 
white     precipi- 
tate or  turbidity 
indicates  sine. 

MEATS  15 

FISH  SALT  DRIED  AND  OYSTERS 

This  kind  of  meat  is  often  preserved  with  boric  acid  and 
borax.  They  may  be  detected  by  the  method  given  under 
fresh  and  smoked  meat. 

COLORING  MATTER 

Sausages  and  other  chopped  meat  preparations,  together 
with  corned  meat  that  has  been  cured  without  sahpeter, 
are  often  treated  with  artificial  coloring  matter. 

Aniline  red  and  cochineal  carmine  are  usually  employed 
for  this  purpose.  The  former  may  be  detected,  according 
to  Allen,  by  picking  the  meat  apart  and  treating  it  with 
methylated  spirit,  strain  or  filter  the  extract  and  take  up 
with  water.  Then  a  piece  of  white  wool  (nun's  veiling  will 
do)  is  immersed  in  the  boiling  liquid  and,  if  it  is  dyed  red, 
rosaniline  is  present. 

Cochineal-carmine  may  be  detected  by  the  method  used 
by  Klinger  and  Bujard.  Cut  up  fine  about  20  grams  of 
the  meat  and  heat  in  a  water-bath  with  water  and  glycerine 
mixed  in  equal  parts.  If  the  above  coloring  matter  is 
present  the  liquid  will  become  quite  red  in  color,  if  not 
present  a  slight  yellow  color  results  from  this  treatment. 
If  a  spectroscope  is  available  this  dye  is  easily  recognized. 

STARCH 

In  Sausage,  Deviled  Meat,  and  Similar  Products 
Cracker  and  bread  cnmibs  are  often  added  to  these 
preparations  and  their  presence  is  best  detected  by  examin- 
ing the  amount  of  starch  present.  Do  this  by  boiling  some 
of  the  sample  in  water,  and  when  cool  adding  a  drop  or  two 
of  iodin  reagent.    The  usual  blue  color  is  produced  if  much 


i6  PURE  FOOD   TESTS 

starch  is  present.  If  there  is  only  a  little  starch,  it  may  be 
necessary  to  examine  it  under  the  microscope  to  determine 
whether  the  starch  is  from  the  pepper  and  other  spices  used 
or  from  some  cereal. 

DISEASED  MEAT 

The  jollowing  method  is  recommended  by  Ebers.  —  Hold  a 
small  piece  of  the  suspected  meat  over  a  mixture  of  i  cc. 
hydrochloric  acid,  3  cc.  alcohol,  and  i  cc.  of  ether.  The 
formation  of  ammonium  chlorid  fumes  shows  that  decom- 
position has  begun.  Do  not  mistake  the  fumes  of  the  acid 
for  those  of  ammonium  chlorid. 

HORSE  FLESH 
In  Sausage  and  Mince  Meat 

This  sophistication  is  not  common  in  this  country.  Horse 
flesh  is  detected  by  testing  for  glycogen,  which  is  present  in 
it  in  larger  quantities  than  in  other  meats. 

Courley  &"  Coremon's  Test.  —  Boil  50  grams  of  the  meat 
for  a  half  hour  with  water,  strain,  and  to  a  portion  of  the 
filtrate  add  a  few  drops  of  potassium  iodid-iodin  solution 
(potassium  iodid  0.4  gram;  iodin  o.i  gram;  water  20  cc). 
If  considerable  horse  meat  is  present  the  glycogen  will  color 
the  liquid  dark  brown,  which  disappears  on  heating,  but 
returns  on  cooling. 

EGGS 

It  sometimes  happens  that  one  wishes  to  know  the  age  of 
eggs  without  opening  them. 

Delarne^s  Test.  —  Place  the  egg  in  a  10  per  cent  solution 
of  common  salt.    Perfectly  fresh  eggs  sink  to  the  bottom. 


MEATS  I'/' 

Those  remaining  immersed,  but  suspended  in  the  liquid,  are 
at  least  three  days  old,  while  those  rising  to  the  surface  and 
floating  are  more  than  five  days  old.  The  older  the  egg, 
the  higher  it  floats  and  the  more  it  will  stand  on  end.  This 
test  is  not  applicable  to  eggs  that  have  been  preserved. 

Hold  the  egg  between  a  bright  light  and  the  eye,  and  if 
the  air  chamber  is  small,  and  no  dark  spots  but  instead  a 
rather  uniform  rose-colored  tint  is  seen,  the  egg  is  fresh. 
If  the  contents  appear  cloudy  and  the  air  chamber  larger, 
the  egg  is  not  fresh.  The  darker  the  contents  of  the  egg 
the  older  it  is. 


CHAPTER   III 
CEREAL  PRODUCTS 

FLOUR 

Sometimes  a  cheaper  or  inferior  grade  of  flour  is  sub- 
stituted for  one  of  higher  quaUty,  and  even  a  different  kind 
of  flour  may  be  substituted,  as  corn  meal  in  wheat  flour,  or 
wheat  in  rye  flour.  Alum  may  be  added  by  millers  to 
cover  up  traces  of  bad  flour,  and  by  bakers  to  make  the 
bread  white  when  a  bad  or  cheap  flour  is  being  used. 
Copper  sulfate  also  may  be  added  to  improve  the  appear- 
ance. Occasionally  rye  flour  is  made  from  rye  upon  which 
ergot  has  developed.  Stannous  chlorid  and  potassium 
carbonate  are  added  to  ginger  cake  to  give  the  same  color 
to. the  product  made  of  molasses  and  a  poor  grade  of  flour 
as  that  made  from  good  flour  and  honey. 

ALUM 

Wynther  Blyth  Method.  —  Add  a  Uttle  water  to  the 
sample  and  macerate.  Soak  pieces  of  gelatin  in  the  solu- 
tion and  leave  for  a  half  day,  remove  the  gelatin  and  dip 
the  pieces  in  a  mixture  of  equal  volumes  of  a  fresh  tincture 
of  logwood  and  a  saturated  solution  of  ammonium  car- 
bonate.   The  gelatin  strips  will  turn  blue  if  alum  is  present. 

Bell  6*  Carter  Method.  —  Make  a  fresh  5  per  cent  tinc- 
ture of  logwood  in  methyl  alcohol.  Dampen  about  10 
grams  of  the  flour  with  water  and  add  i  cc.  of  the  logwood 
tincture  and  the  same  quantity  of  a  saturated  solution  of 
ammonium  carbonate.  Pure  flour  gives  a  pinkish  color 
which  fades  to  buff  or  brown.    The  presence  of  alum 

z8 


CEREAL  PRODUCTS  19 

produces  a  lavender  or  bluish  tint  which  becomes  more 
distinct  as  it  dries. 

COPPER  SULFATE 

This  adulterant  may  be  detected  in  either  flour  or 
bread,  by  soaking  the  flour  or  bread  in  a  dilute  solution  of 
potassium  ferrocyanid  acidulated  with  acetic  acid.  If 
copper  be  present  a  purplish  or  reddish-brown  coloration 
will  be  produced. 

SUBSTITUTED  FLOURS 

Examine  the  flour  under  the  microscope  and  compare 
with  a  sample  known  to  be  pure.  Any  adulteration  of 
the  flour  by  substituting  another  flour  may  be  determined 
by  comparison  with  pure  samples  of  the  different  flours. 

Vogel's  Method.  — "Make  a  mixture  of  alcohol  (70  per 
cent)  95  parts,  hydrochloric  acid  5  parts.  Treat  a  sample 
of  the  flour  in  a  test  tube  with  this  reagent.  Shake  well. 
Heat  to  boiling  and  allow  to  settle.  A  colorless  fluid 
shows  the  flour  to  be  pure,  a  straw-colored  tint  indicates 
the  presence  of  gruff s  with  bran,  an  orange-yellow  proves 
the  presence  of  corn-cockle  flour,  a  flesh-colored  liquid 
indicates  the  presence  of  ergot,  while  a  green  color  indicates 
buckwheat  flour. 

Corn  Meal  in  Wheat  Flour 

Kraemer  claims  to  be  able  to  detect  as  small  amount  as  5 
per  cent  of  maize  in  wheat  flour,  by  the  following  test.  —  Mix 
a  gram  of  the  flour  with  15  cc.  of  good  glycerin,  and  heat  to 
boiUng  for  a  short  time.  If  corn  meal  is  present,  there  will 
be  an  odor  like  that  of  pop  corn. 


20  PURE  FOOD   TESTS 

Wheat  in  Rye  Flour 

Kleeburg  recommends  the  jollowing  test.  —  A  little  of  the 
flour  is  mixed  on  a  piece  of  common  window  glass  or  micro- 
scope slide,  with  sufficient  water  (at  45°  C.)  to  float  the 
flour  particles.  Spread  the  mixture  out  over  the  glass,  and 
press  another  glass  down  upon  it.  When  wheat  flour  is 
present,  white  spots  will  be  seen,  and  if  the  glasses  are  slid 
upon  each  other  the  spots  will  pull  out  into  threads,  and 
the  thicker  and  longer  they  are  the  more  wheat  flour  there 
is  present. 

Ergot  m  Rye  Flour 

Boettger  gives  the  jollowing  chemical  test  for  ergot.  —  Heat 
10  to  15  minutes  with  an  equal  quantity  of  ether,  adding  a 
few  crystals  of  oxalic  acid.  When  ergot  is  present  a  red- 
dish color  develops. 

Another  Method.  —  Bui.  51,  Bureau  of  Chem. 

Digest  20  grams  of  the  suspected  flour,  with  boiling 
alcohol,  till  no  more  color  is  extracted.  Add  i  cc.  of  sul- 
furic acid  (1:3),  and  if  ergot  is  present  the  solution  will  be 
colored  red. 

BREAD 
ALUM 

Moisten  a  piece  of  the  bread  with  water,  and  then  with  a 
logwood  solution  (5  grams  logwood  digested  in  100  cc.  of 
alcohol).  If  alum  is  present  the  bread  will  become  laven- 
der blue  in  two  or  three  hours.  Pure  bread  would  have  a 
red-brown  tint.  To  prove  the  presence  of  alum,  the  blue 
color  must  be  permanent  at  the  temperature  of  boiling 
water.     (The  logwood  used  in  this  test  must  be  pure.) 


CEREAL  PRODUCTS  21 

Blyth's  Test.  —  Macerate  150  grams  of  the  sample  for 
45  or  50  hours  in  a  couple  liters  of  water;  after  straining 
through  muslin,  evaporate  to  a  small  volume  over  a  low 
flame.  Immerse  a  strip  of  gelatin  in  this  liquid,  and  then 
in  a  logwood  solution  (same  as  in  last  test),  and  if  alum  is 
present  it  will  acquire  the  lavender  color. 

If  the  bread  in  either  of  these  tests  is  sour,  the  following 
modification  (Vanderplanken)  must  be  made.  Reduce  15 
grams  of  the  sample  to  a  paste  with  water  and  some  pure 
chlorid  of  sodium,  adding  10  drops  of  a  fresh  alcoholic 
solution  of  logwood,  after  which  add  5  grams  of  pure  potas- 
sium carbonate.  Mix  well,  and  after  washing  with  100  cc. 
of  water  into  a  vessel  allow  to  settle.  If  alum  is  present 
the  liquid  will  soon  become  reddish-violet,  and  if  not  present 
it  will  be  blue. 

COPPER  SULFATE 

See  Test  for  Copper  Sulfate  in  Flour 

GINGER    CAKE 

Tin  may  be  detected  by  the  method  for  heavy  metals 
under  meat. 


CHAPTER  IV 

LEAVENING  MATERIALS 

BAKING  POWDERS 

Baking  powders  consist  of  bicarbonate  of  soda  and  an 
acidifying  agent  as  acid  potassium  tartrate,  acid  calcium 
phosphate,  tartaric  acid  or  alum.  Starch  is  generally 
added  as  a  "filler,"  the  object  being  to  prevent  the  in- 
gredients acting  too  soon.  Some  powders  contain  both 
acid  calcium  phosphate  and  alum.  The  kind  of  powder 
is  determined  by  testing  for  these.  Gypsum  has  been 
added  to  baking  powders  to  increase  the  weight. 

FLOUR  OR  STARCH 

Add  to  a  small  portion  of  the  sample  a  few  drops  of 
tincture  of  iodin  (made  by  dissolving  iodin  in  alcohol). 
A  blue  coloration  indicates  the  presence  of  starch. 

TARTARIC  ACID 
Free  or  Combined 

Wolffs  Method.  —  If  no  starch  is  present,  mix  a  little  of 
the  powder  with  some  dry  resorcin.  Add  a  few  drops  of 
sulfuric  acid  and  heat  gently.  A  rose-red  color  forms  if 
tartaric  acid  or  tartrates  are  present.    The  color  should 

22 


LEAVENING  MATERIALS  23 

disappear  when  diluted  with  water.  When  starch  is 
present,  mix  well  by  shaking  about  5  grams  of  the  powder 
with  250  cc.  of  cold  water.  Let  the  insoluble  matter 
settle  and  pour  the  Uquid  upon  a  filter.  Evaporate  the 
filtrate  to  dryness,  treat  the  powdered  residue  with  a  few 
drops  of  a  I  per  cent  solution  of  resorcin.  Add  3  cc.  of 
strong  sulfuric  acid,  heat  slowly.  A  rose-red  color  forms 
if  tartaric  acid  is  present.  The  color  should  be  destroyed 
on  the  addition  of  water.  This  test  is  apphcable  in  the 
presence  of  phosphates  and  the  acid  may  be  free  or  com- 
bined. 

TARTARIC  ACID 

Free 

Make  an  absolute  alcohohc  extract  of  5  grams  of  the 
powder  and  evaporate  the  alcohol.  Add  sufficient  dilute 
ammonia  to  dissolve  the  residue,  place  in  a  test  tube  and 
drop  in  a  crystal  or  two  of  silver  nitrate.  Heat  gently, 
and  a  silver  mirror  will  form  if  tartaric  acid  is  present. 


PHOSPHORIC  ACID 

Place  5  grams  of  the  sample  in  a  porcelain  dish  and 
ignite.  Add  nitric  acid  to  the  residue,  heat  for  a  short 
time,  dilute  and  filter.  Add  a  solution  of  ammonium 
molybdate,  warm  sUghtly,  If  phosphoric  acid  is  present 
a  copious  yellow  precipitate  of  ammonium  phosphomolyb- 
date  will  form.  Do  not  be  deceived  by  the  shght  precipi- 
tate which  always  forms  if  flour  is  present,  since  the  ash 
of  flour  always  contains  a  Uttle  calcium  phosphate. 


24         PURE  FOOD  TESTS 
SULFATES 

CALaUM,   ETC. 

Boil  a  portion  of  the  sample  gently  with  strong  hydro- 
chloric acid,  add  barium  chlorid.  A  white  precipitate  of 
barium  sulfate  will  form  if  sulfuric  acid  is  present. 

GYPSUM 

Calcium  Sulfate 

Ash  a  portion  of  the  sample  and  make  the  usual  quali- 
tative tests  for  calcium  sulfate. 

AMMONIUM  SALTS 

Extract  a  few  grams  of  the  sample  with  cold  water, 
boil  the  extract  with  sodium  hydroxid  and  place  a  piece  of 
moist  red  litmus  paper  in  the  steam.  It  will  be  colored 
blue  if  ammonia  is  present. 

ALUM 

Reduce  to  an  ash  about  2  grams  of  the  powder  in  a 
platinum  dish.  Extract  with  boiling  water,  add  am- 
monium chlorid  solution  to  the  filtrate  until  a  distinct 
odor  of  ammonia  is  given  off. 

If  a  flocculent  precipitate  forms  it  indicates  the  presence 
of  alum. 

This  test  for  alum  is  applicable  in  the  presence  of 
phosphates. 

Mrs.  Richards.  —  Cover  some  logwood  chips  (they  must 
be  pure)  with  water  and  bring  to  a  boil.    Repeat  this  four 


LEAVENING  MATERIALS  25 

times,  saving  only  the  last  decoction.  Shake  some  of  the 
sample  (a  couple  of  teaspoonfuls)  in  a  beaker  half  full  of 
water.  When  it  ceases  effervescing,  strongly  acidify  with 
acetic  acid.  Add  a  few  drops  of  the  logwood  extract,  and 
if  alum  is  present  a  bluish-red  color  will  appear. 


CREAM  OF  TARTAR 

Cream  of  tartar  is  bitartrate  of  potassium  and  is  ob- 
tained from  the  lees  deposited  in  wine  casks.  If  gypsum 
has  been  used  to  clarify  the  wine,  it  will  be  present  in  the 
cream  of  tartar  as  calcium  tartrate. 

Other  adulterants  of  cream  of  tartar  are  acid  calcium 
phosphate,  starch,  gypsum  and  alum. 

TARTARIC  ACID 
Free  or  Combined 

If  the  sample  is  known  to  be  free  from  starch  the  follow- 
ing test  may  be  made: 

Mix  a  bit  of  the  powder  with  a  small  quantity  of  dry 
resorcin  and  add  a  few  drops  of  concentrated  sulfuric  acid. 
Heat  slowly,  and  if  a  rose-red  color  forms,  which  disap- 
pears when  diluted  with  water,  there  is  present  either 
tartaric  acid  or  a  tartrate. 

When  the  sample  contains  starch,  shake  about  4  or  5 
grams  of  it  a  number  of  times  with  250  cc.  of  cold  water 
in  a  large  flask.  Pour  on  a  filter  after  the  insoluble  ma- 
terial has  settled  and  evaporate  the  filtrate  to  dryness. 
The  residue  is  to  be  tested  for  tartaric  acid  and  tartrates, 
the  same  as  when  starch  was  absent. 


26  PURE  FOOD  TESTS 

ALUMINIUM  SALTS 

Mix  equal  quantities  (about  i  gram)  of  the  sample  and 
sodium  carbonate  and  burn  to  an  ash.  Extract  with 
boiling  water  and  filter.  Add  to  this  filtrate  enough 
ammonium  chlorid  solution  to  cause  a  distinct  evolution 
of  ammonia.  The  formation  of  a  flocculent  precipitate 
shows  the  presence  of  aluminium.  This  test  may  be  used 
when  phosphates  are  present. 

AMMONIA 

Present  in  the  Form  of  Ammonium  Alum  or  Ammonium 
Carbonate 

Make  a  cold  water  extract  of  the  powder  and  boil  it 
with  sodium  hydroxid.  Test  the  steam  with  moist  red 
litmus  paper. 

CALCIUM  PHOSPHATE 

Ignite  a  sample  of  the  cream  of  tartar  and  test  the 
same  as  for  phosphoric  acid  under  baking  powders, 

EARTHY  MATERIALS 

Treat  the  sample  with  warm  potassium  hydroxid.  A 
residue  indicates  some  earthy  material. 

LIME 

When  phosphates  are  absent  ignite  the  sample  and 
dissolve  the  residue  in  distilled  water,  slightly  acidified 
with  hydrochloric  acid,  filter,  add  a  few  drops  of  am- 
monium oxalate  and  an  excess  of  ammonium  hydroxid. 
A  white  precipitate  indicates  the  presence  of  lime. 


CHAPTER  V 

CANNED  AND  BOTTLED  VEGETABLES 

No  class  of  foods  on  the  market  has  less  need  for  anti- 
septics than  canned  goods,  yet  their  use  is  rather  common. 
Products  thus  treated  are  easier  canned  and  are  not  so  apt 
to  spoil.  The  chemicals  used  as  preservatives  are  sulfurous 
acid,  and  the  sulfites,  salicylic  acid  and  saccharin,  benzoic 
acid,  and  sometimes  formaldehyde.  Sulfurous  acid  is 
used  to  bleach  such  foods  as  canned  corn.  Saccharin 
possesses  some  antiseptic  properties,  but  its  main  use  is  as 
a  sweetener.     Alum  is  used  to  make  pickles  hard  and  crisp. 

Some  canned  or  bottled  goods,  as  tomato-catsup,  is  col- 
ored with  cochineal  or  coal-tar  dyes.  Green  pickles,  beans, 
peas,  and  such  vegetables  are  colored  by  copper  salts  or 
are  cooked  in  copper  vessels,  with  the  addition  of  acetic 
acid,  hence  the  beautiful  green  color.  Turmeric  is  some- 
times used  to  color  mixed  pickles. 

The  heavy  metals  as  lead,  zinc,  and  tin  are  generally 
present  in  canned  goods,  the  amount  varying  with  the  cor- 
rosive power  of  the  vegetable. 

When  there  is  a  year  of  scarcity  in  corn,  peas,  beans,  and 
such  vegetables,  the  dried  product  is  often  soaked  and 
canned.  Some  of  this  goods  is  sold  for  the  regular  green 
vegetable,  while  some  may  be  properly  marked  "Soaked 
Goods." 

27 


28  PURE  FOOD  TESTS 

PRESERVATIVES 

It  is  best  to  make  a  systematic  examination  for  the  diflfer- 
ent  preservatives.  The  sample  may  be  prepared  by  mixing 
50  grams  of  the  pulped  material  with  sufficient  water  in  a 
250  cc.  graduated  flask.  Add  phosphoric  acid  till  distinctly 
acid  in  reaction.  Fill  to  the  mark  with  water.  Place  in  a 
distilling  flask,  and  distil  in  a  linseed  oil  or  a  paraffin  bath 
till  30  cc.  have  been  collected.  Save  this  distillate  for  the 
following  tests. 

Formaldehyde 

To  5  cc.  of  the  above  distillate  in  a  test  tube,  add  2  or  3 
drops  of  a  I  per  cent  aqueous  solution  of  phenol  and  mix 
well.  Incline  the  tube  and  carefully  pour  down  the  side 
5  cc.  of  concentrated  commercial  sulfuric  acid  so  that  the 
two  liquids  do  not  mix.  If  formaldehyde  is  present  there 
will  be  a  crimson  zone  at  the  plane  of  union  of  the  solutions. 
This  coloration  takes  place  when  the  formaldehyde  is 
present  in  the  proportion  of  i  part  in  100,000  parts.  When 
there  is  a  greater  quantity  of  formaldehyde  present  a  white 
turbidity  or  a  light-colored  precipitate  forms  above  the 
coloring. 

Phenylhydrazine  Hydrochloric  Test.  —  Dissolve  2  grams 
of  phenylhydrazine  hydrochlorid  and  3  grams  of  sodium 
acetate  in  20  cc.  of  water.  Add  2  to  4  drops  of  this  reagent 
and  the  same  number  of  drops  of  sulfuric  acid  to  i  or  2 
cc.  of  the  above  distillate,  to  be  examined  in  a  test  tube.  A 
green  coloration  is  produced  when  formaldehyde  is  present. 

Hydrochloric  Acid  Test.  —  Add  5  cc.  of  the  distillate  to 
be  tested  to  about  5  cc.  of  milk  known  to  be  pure,  and  about 
10  cc.  of  concentrated  hydrochloric  acid  (sp.  gr.  1.2)  which 
contains  i  cc.  of  a  lo  per  cent  ferric  chlorid  solution  to  each 


CANNED  AND  BOTTLED  VEGETABLES     29 

500  cc.  of  the  acid.  Heat  slowly  to  80°  or  go°  C.  over  the 
free  flame,  agitating  it  at  the  same  time  to  break  up  the 
curd.     A  violet  coloration  indicates  formaldehyde. 

SuLFUROUS  Acid  and  the  Sulfites 

Free  sulfurous  acid  is  not  largely  used  as  a  food  pre- 
servative, though  its  salts  are  quite  commonly  employed. 

Detection.  —  Mix  150  grams  of  the  finely  ground  sample 
with  enough  water  to  make  a  thin  paste.  Acidify  with 
phosphoric  acid  and  distil  till  25  cc.  have  been  collected. 
(The  delivery  tube  of  the  condenser  should  dip  below  the 
surface  of  a  little  water.)  Treat  the  distillate  with  a  few 
drops  of  bromine  water  and  boil  for  a  short  time.  If  a 
precipitate  forms  on  the  addition  of  barium  chlorid  the 
presence  of  sulfurous  acid  is  indicated. 

Salicylic  AaD 

Acidify  50  cc.  of  the  sample  with  sulfuric  acid,  and  shake 
vigorously  with  50  cc.  of  a  mixture  of  equal  parts  of  ether 
and  petroleum  spirit.  When  the  liquids  have  separated, 
draw  off  as  much  as  possible  of  the  solvent  and  filter.  If 
an  emulsion  forms  use  a  centrifugal  machine,  and  evaporate 
with  a  small  flame.  If  needle-shaped  crystals  form,  sali- 
cylic acid  is  present.  Add  a  few  drops  of  water  and  a  drop 
of  very  dilute  ferric  chlorid  solution  in  such  a  way  that  the 
solutions  will  come  together  slowly.  The  presence  of 
salicylic  acid  gives  a  purple  or  violet  color. 

Saccharin 

This  is  used  quite  extensively  as  a  sweetening  agent  in 
canned  sweet  com,  and  other  similar  products. 

Macerate  about  20  grams  of  the  sample  after  mixing  with 


30  PURE  FOOD  TESTS 

30  to  40  cc.  of  water  and  strain  through  muslin.  Acidify 
with  I  or  2  cc.  of  sulfuric  acid  (i  to  3)  and  extract  with 
ether.  (If  an  emulsion  forms,  use  a  centrifugal  machine.) 
Separate  the  ether  layer  and  let  the  ether  evaporate  spon- 
taneously and  use  the  residue  in  the  following  tests: 

Take  up  a  part  of  the  residue  with  water  and  taste.  If  it 
is  very  sweet  saccharin  is  present.     Confirm  by  the  following: 

Schmidt's  Test.  —  Add  about  i  gram  of  sodium  hydroxide 
to  another  part  of  the  residue,  and  heat  in  an  air-oven  or 
oil  bath,  for  half  an  hour  at  about  250°  C,  to  convert  the 
saccharin  into  salicylic  acid.  After  it  has  cooled,  acidify 
with  sulfuric  acid,  extract  and  test  for  salicylic  acid  with 
2  or  3  drops  of  ferric  chlorid  solution,  letting  the  solutions 
come  together  slowly.  A  purple  or  violet  coloration  proves 
the  presence  of  salicylic  acid,  which  in  turn  indicates  the 
presence  of  saccharin.  This  test  cannot  be  used  if  salicylic 
acid  was  used  as  a  preservative  in  the  original  product.  A 
test  for  the  acid  should  first  be  made. 

Bornstein's  Test.  —  Heat  the  remainder  of  the  above 
ether  residue  with  resorcin  and  a  very  little  sulfuric  acid  till 
it  begins  to  swell.  (It  is  best  to  do  this  heating  in  a  test- 
tube.)  Let  cool  till  the  action  stops,  heat  again  and  rejaeat 
the  operation  several  times.  After  cooling  the  last 
time,  dilute  with  water  and  add  sodium  hydrate  till 
neutral.  If  saccharin  is  present,  there  will  be  a  red-green 
fluorescence. 

Benzoic  Acid 

Acidify  50  cc.  of  the  sample  with  sulfuric  acid  and  shake 
vigorously  with  50  cc.  of  a  mixture  of  equal  parts  of  ether 
and  petroleum  spirit.  Let  the  liquids  separate,  then  draw 
off  as  much  as  possible  of  the  solvent  and  filter.     (Use  a 


CANNED  AND  BOTTLED  VEGETABLES     31 

centrifugal  machine  if  an  emulsion  forms.)  Separate  the 
extract  into  2  parts  and  evaporate  each  to  dryness  over  a 
small  flame  and  make  the  following  tests: 

Ferric  Chlorid  Test.  —  Dissolve  one  of  these  residues  in 
ammonia,  and  evaporate  to  dryness  on  a  water-bath.  Take 
up  the  residue  with  warm  water,  filter,  and  collect  the  filtrate 
in  a  small  test  tube.  Add  a  drop  of  ferric  chlorid  solution, 
and  if  benzoic  acid  is  present  a  characteristic  flesh  or  brown- 
ish colored  precipitate  of  ferric  benzoate  forms.  Some- 
times in  such  products  as  sweet  pickles,  a  basic  ferric  acetate 
precipitate  comes  down  and  the  following  test  had  better 
be  applied. 

Peter's  Method.  —  Take  about  o.  i  gram  of  the  second 
part  of  the  above  ether  residue,  place  in  a  large  test  tube 
(about  50  cc.)  and  dissolve  in  5  to  8  cc.  of  concentrated 
sulfuric  acid.  Add  from  0.5  to  0.8  gram  of  barium  peroxide, 
a  little  at  a  time.  Shake  each  time  and  cool  in  water  if 
necessary.  This  should  produce  a  permanent  froth  on 
the  sulfuric  acid.  Let  stand  25  or  30  minutes,  then  fill  the 
tube  three  fourths  full  of  water,  shake  and  cool  rapidly  to 
the  temperature  of  the  room,  and  filter  off  the  barium 
sulfate.  Extract  with  chloroform  or  ether.  Remove  the 
extract  and  test  it  for  salicylic  acid  with  dilute  ferric  chlorid. 
(See  first  test  under  salicylic  acid.)  In  this  method  sali- 
cylic acid  must  first  be  proven  absent. 

Mohler's  Test.  —  Treat  the  remainder  of  the  second  part 
of  the  above  ether  residue  with  2  or  3  cc.  of  concentrated 
sulfuric  acid.  Heat  till  white  fumes  appear.  Add  a  few 
crystals  of  potassium  nitrate  and  when  cool  dilute  with 
water.  Add  an  excess  of  ammonia,  then  a  drop  or  two  of 
ammonium  sulfid.  If  a  red  color  appears  immediately 
on  the  surface,  it  shows  the  presence  of  benzoic  acid. 


32  PURE  FOOD  TESTS 

COLORING  MATTER  IN  CATSUPS  AND 
TOMATOES 

Cochineal 

Girard  and  Dupre  Test.  —  Shake  well  a  portion  of  the 
sample  with  water  and  filter,  acidify  with  hydrochloric  acid, 
then  extract  with  amyl  alcohol,  and  if  cochineal  is  present 
the  extract  will  be  colored  yellow  or  orange,  the  particular 
shade  depending  on  the  amount  of  cochineal  present. 
Remove  the  amyl  alcohol  and  wash  with  water  until  it  is 
neutral.  To  half  of  this,  add  a  very  dilute  solution  of 
uranitun  acetate,  drop  by  drop,  and  shaking  well  after  the 
addition  of  each  drop.  Cochineal,  if  present,  will  produce 
a  characteristic  emerald-green  color. 

Confirm  by  adding  a  drop  or  two  of  ammonia  to  the 
second  half  of  the  amyl  alcohol  extract  and  a  violet  colora- 
tion will  be  produced  if  cochineal  is  present. 

Coal-Tar  Coloring  Matter 

Sostegni  and  Carpentieri  Test.  —  Free  from  grease  a 
piece  of  woolen  cloth  (nun's  veiling  will  do)  by  boiling  first 
in  very  dilute  caustic  soda  solution  and  then  in  water. 
Acidify  a  portion  of  the  sample  with  2  to  4  cc.  of  lo  per 
cent  solution  of  hydrochloric  acid  and  filter.  Strips  of  the 
cleansed  cloth  are  boiled  in  this  filtrate  for  5  or  10  minutes, 
then  removed,  washed  in  water  and  boiled  with  very  dilute 
hydrochloric  acid  solution.  Wash  out  the  acid  and  dis- 
solve the  color  from  the  cloth  by  boiling  in  a  solution  of 
ammonium  hydroxid  (i  to  50).  (The  time  required  will 
depend  upon  the  dye  present.)  Remove  the  cloth  from 
the  solution  and  acidify  the  latter  with  hydrochloric  acid 
and  another  piece  of  the  cleansed  cloth  is  immersed  and 


CANNED  AND  BOTTLED  VEGETABLES     33 

again  boiled.  This  second  dyeing  fixes  only  coal-tar  colors 
on  the  cloth,  hence,  no  fear  of  mistaking  them  for  the  natural 
color  of  the  vegetable. 

IN  GREEN  PICKLES,  BEANS,  PEAS,  ETC 
Copper  Salts 

Burn  20  grams  of  the  sample  to  an  ash  and  wet  the  ash 
with  concentrated  nitric  acid,  dilute  with  water  and  boil. 
Add  ammonia  till  strongly  alkaline  and  filter.  If  the 
filtrate  is  blue,  copper  is  present. 

Confirm  by  acidifying  the  filtrate  with  acetic  acid  and 
adding  potassium  ferrocyanid.  A  red  or  brownish  pre- 
cipitate or  coloration  proves  the  presence  of  copper.  The 
test  for  other  heavy  metals  may  be  made  by  the  general 
method  given  under  meats.  • 

IN  MIXED  PICKLES 

Turmeric 

Shake  with  alcohol  to  extract  the  color.  Soak  a  piece  of 
filter  p  per  in  the  extract  and  dry  in  an  air  oven  at  100°  C. 
Wet  the  filter  paper  with  a  weak  solution  of  boric  acid  to 
which  a  very  little  hydrochloric  acid  has  been  added.  If 
turmeric  is  present,  a  cherry-red  color  will  appear  when  the 
filter  paper  is  dry. 

"SOAKED"   VEGETABLES 

Peas,  Beans,  and  Corn 

There  is  really  no  chemical  test  for  this  class  of  foods. 
Certain  helpful  directions  given  in  Bui.  65,  p.  54,  of  the 
Bureau  of  Chem.,  will  assist  in  identifying  such  goods. 


34  PURE  FOOD  TESTS 

All  or  nearly  all  of  the  green  color  of  peas  and  beans  is 
destroyed  by  the  process  of  "soaking."  They  have  the 
appearance  of  the  well-matured  product,  and  are  firm  and 
mealy  with  well-formed  cotyledons.  The  process  of  soak- 
ing starts  the  growth  of  the  caulicle  of  the  pea.  The  kernel 
of  com  is  plump  and  hard  and  does  not  have  the  milky 
consistency  of  the  immatured  product.  The  characteristic 
succulence  of  the  green  pea,  bean,  and  corn  is  absent  in  the 
soaked  product. 

Alum  in  Pickles 

This  is  sometimes  added  to  the  pickling  solution  to  pro- 
duce hardness  and  crispness. 

Burn  to  ash  a  sample  of  the  pickles,  and,  if  they  are  free 
from  copper,  fuse  in  a  platinum  dish  with  sodium  car- 
bonate. Extract  with  boiling  water,  and  after  filtering 
add  ammonium  chlorid  solution.  If  alum  is  present,  a 
flocculent  precipitate  will  form. 

Examination  of  the  Can  or  Box  in  which  Vegetables 
ARE  Sealed 

Generally  when  the  ends  of  a  can  are  convex,  instead  of 
plane  or  concave,  it  is  spoiled.  In  the  souring  of  canned 
sweet  corn,  it  is  exceptional  that  the  ends  are  forced  outward. 

Strike  the  can  and  the  spoiled  cans  will  give  a  dull  sound 
while  the  good  ones  will  give  a  distinct  tone.  Some  prac- 
tice will  be  necessary  to  use  this  test. 

One  can  judge  of  the  amount  of  tin  dissolved  by  the 
corrosion  of  the  inside  of  the  can. 

Reject  cans  that  show  much  rust  around  the  cap  on  the 
inside  of  the  head. 


CANNED  AND  BOTTLED  VEGETABLES     35 

If  more  than  one  hole  is  found  soldered  in  the  cap,  reject 
the  can.  Cans  of  salmon  are  the  only  exception  that  has 
come  to  the  author's  notice.  A  second  hole,  in  general, 
indicates  that  decomposition  had  set  in  and  the  can  had 
been  punctured  and  resealed. 


CHAPTER  VI 

FRUITS   AND    FRUIT    PRODUCTS 

Salicylic  acid,  benzoic  acid,  and  saccharin  are  used  to 
preserve  fruits.  The  last  is  also  added  as  a  sweetener 
instead  of  sugar.  Many  fruit  products  lose  their  color 
with  age,  and  to  give  them  a  lasting  color  they  are  treated 
with  a  coal-tar  dye,  cochineal,  acid  magenta,  or  caramel. 

A  very  small  per  cent  of  the  jams  and  jellies  sold  are 
strictly  pure.  These  cheap  products  are  made  up  prin- 
cipally of  apple  juice  and  commercial  glucose;  artificial 
essences  are  added  to  imitate  the  real  flavor. 

In  cheap  jellies  made  of  apple  juice  and  glucose  syrup, 
a"coaguIator"  is  used;  usually  sulfuric  acid  and  alum, 
also  citric  and  tartaric  acids  may  be  used  for  this  purpose. 

Starch,  gelatin,  and  agar  are  used  as  gelatinizing  agents. 

Fruits  put  up  in  tin  cans  may  dissolve  the  heavy  metals 
as  tin,  zinc,  lead,  and  even  arsenic. 

PRESERVATIVES 

Preparation  of  the  Sample.  —  Dissolve  25  or  30  grams  of 
the  sample  in  water  which  has  been  acidified  with  sulfuric 
acid  (i  to  3),  then  extract  with  ether,  and  remove  the  ether 
layer  and  let  it  evaporate  spontaneously.  The  residue 
may  contain  salicylic  acid,  benzoic  acid,  or  saccharin.  Take 
up  with  a  little  water  and  make  the  following  tests: 

36 


FRUITS  AND  FRUIT  PRODUCTS  37 

Salicylic  Acid 

Place  a  few  drops  of  this  extract  in  a  test  tube  and  add  a 
drop  or  two  of  a  0.5  per  cent  solution  of  ferric  chlorid.  If 
salicylic  acid  is  present,  there  will  be  a  purple  coloration. 

Benzoic  Acid 

Mohler^s  Test.  —  Add  2  to  3  cc.  of  strong  sulfuric  acid  to 
a  second  portion  of  the  above  ether  extract  and  heat  until 
white  fumes  appear.  Then  add  a  few  crystals  of  potas- 
sium nitrate  and  heat  again.  Continue  adding  the  nitrate 
and  heating  till  the  solution  is  colorless  or  only  a  very  light 
yellow.  Dilute  with  about  5  cc.  of  water  when  cool, 
neutralize  with  ammonia.  It  should  be  filtered  when  not 
clear  or  when  crystals  of  ammonium  or  potassium  sulfate 
are  formed.  Add  a  few  drops  of  ammoniimi  sulfid  to  the 
filtrate  in  such  a  way  as  to  prevent  the  mixing  of  the  liquids. 
The  sulfid  will  be  on  top.  If  a  bright  cherry-red  color 
forms  where  the  two  liquids  meet,  either  benzoic  acid  or 
saccharin  is  present.  Distil  and  the  benzoic  acid  will  pass 
over,  extract  the  distillate  in  the  usual  way  and  apply  the 
above  test  to  it  for  benzoic  acid. 

Saccharin 

Taste  a  third  portion  of  the  ether  extract.  A  very  sweet 
taste  indicates  saccharin.  A  further  test  can  be  made  by 
adding  i  or  2  grams  of  sodium  hydroxid  to  the  rest  of  the 
ether  extract  and  heating  a  half  hour  in  an  oil  bath  at 
250°  C.  Dissolve  in  water  when  cool,  acidify  with  dilute 
sulfiu-ic  acid  and  extract  with  ether.  The  saccharin  will  have 
been  converted  into  salicylic  acid,  which  may  be  identified 
by  the  usual  test  for  that  acid.  This  test  presupposes  the 
absence  of  salicylic  acid  in  the  original  material. 


38  PURE  FOOD  TESTS 

COLORING  MATTER 
Coal-Tar  Dyes 

To  attempt  to  identify  the  particular  dye  used  in  every 
case  would  be  quite  beyond  the  object  of  this  set  of  simple 
tests.  A  general  test  showing  the  presence  of  a  coal-tar 
dye  is  probably  all  that  is  usually  desired. 

Sostegni  and  Carpentieri  Test.  —  Such  a  test  may  be 
made  by  dissolving  15  grams  of  the  fruit  product  in  100  cc. 
of  water,  filtering  and  acidifying  with  a  small  quantity  of  a 
10  per  cent  solution  of  hydrochloric  acid  and  again  filtering. 
Place  in  the  filtrate  strips  of  white  woolen  cloth  (nun's 
veiling  will  do)  which  have  been  freed  from  grease  by  boil- 
ing first  in  very  dilute  caustic  soda  solution,  then  in  water, 
and  boil  for  5  to  10  minutes.  Remove  the  cloth  and  wash 
it  in  water,  then  boil  in  very  dilute  hydrochloric  acid.  Stir 
the  cloth  in  water  to  remove  the  acid  and  dissolve  the  color 
by  boiling  in  a  solution  of  ammonium  hydroxid  (i  to  50). 
The  time  required  will  depend  upon  the  particular  dye 
used.  Remove  the  cloth  from  the  solution  and  acidify  the 
latter  with  hydrochloric  acid,  a  slight  excess  is  better,  and 
another  piece  of  the  cleansed  cloth  is  immersed  and  again 
boiled.  Nothing  but  coal-tar  dyes  will  color  in  this  second 
dyeing. 

Cochineal 

Girard  and  Dupre  Test.  —  See  tests  for  cochineal  under 
"Catsups  and  tomatoes." 

Acid  Magenta 

Girard  and  Dupre.  —  Make  about  100  cc.  solution  of  the 
fruit,  filter,  and  neutralize  with  potassium  hydroxid  (strength 
5  to  100);  about  3  cc.  will  be  needed.     Add  4  cc.  of  mercuric 


FRUITS  AND  FRUIT  PRODUCTS  39 

acetate  solution  (i  to  10),  shake  and  filter.  By  this  treat- 
ment the  filtrate  should  be  colorless  and  slightly  alkaline. 
Add  sulfuric  acid  till  there  is  a  slight  excess.  A  colorless 
solution  indicates  the  absence  of  acid  magenta,  while  a 
light  violet-red  shows  its  presence,  providing  the  amyl- 
alcohol  extract  showed  no  other  dye  to  be  present. 

Caramel 

Amthor^s  Test.  — 10  cc.  of  a  solution  of  the  fruit  is  put 
into  a  deep,  narrow  glass  (a  bottle  may  be  used).  Add  30 
to  50  cc.  of  paraldehyde,  to  be  gaged  by  the  intensity  of 
the  coloring.  Then  add  a  sufl5cient  quantity  of  absolute 
alcohol  to  make  the  solutions  mix.  If  caramel  is  present, 
a  brownish-yellow  to  dark-brown  precipitate  will  be  formed, 
decant,  wash  the  precipitate  once  with  absolute  alcohol, 
dissolve  in  a  little  hot  water  and  filter.  The  shade  of  color 
is  proportional  to  the  amount  of  caramel  present. 

To  verify  the  test,  pour  the  colored  fluid  into  a  freshly 
prepared  solution  of  phenylhydrazin  (2  parts  phenyl- 
hydrazin-hydrochlorid,  3  parts  sodium  acetate,  and  20  parts 
water).  Much  caramel  produces  a  dark-brown  precipi- 
tate in  the  cold,  and  is  hastened  by  slightly  heating.  A 
very  small  amount  of  caramel  will  require  several  hours  to 
precipitate. 

APPLE-JUICE    IN    JELLIES    MADE    OF    SMALL 
FRUITS 

Very  often  cider  is  added  to  other  fruit  juices  to  give  them 
the  proper  consistency  in  jellies,  jams,  and  marmalades. 

Its  presence  may  some  times  be  determined  by  making  the 
usual  starch  test.    A  large  quantity  of  starch  is  normally 


40  PURE  FOOD  TESTS 

present  in  apples,  but  is  less  as  they  ripen,  and  finally  dis- 
appears in  the  ripened  fruit.  There  is  no  starch,  or  only  a 
mere  trace,  in  small  fruits  even  when  green.  It  is  readily 
seen  that  if  the  juice  is  taken  from  green  apples  that  there 
will  be  starch  found  in  the  artificial  jelly  or  jam,  though  its 
absence  does  not  prove  the  absence  of  cider. 
Make  the  starch  test  as  follows: 

STARCH 
In  Jellies,  Jams,  and  Such  Products 

Make  a  solution  of  the  jelly  or  jam  and  destroy  the  color 
by  heating  nearly  to  the  boiling  point  and  adding  dilute 
(i :  3)  sulfuric  acid  and  potassium  permanganate  until 
the  color  is  destroyed.  This  treatment  does  not  affect  the 
starch,  and  when  cool  add  iodin,  preferably  potassium 
iodid-iodin  (potassium  iodid,  0.4  gram;  iodin,  o.i  gram; 
water,  20  cc).  If  a  great  quantity  of  starch  is  present  an 
almost  black  precipitate  will  be  formed.  Smaller  amounts 
give  the  usual  blue  color. 

Whenever  starch  is  found  to  be  present,  it  is  best  to  make 
a  microscopical  examination  in  the  case  of  jams  and 
marmalades.  If  the  starch  is  normally  present  the  grains 
will  be  seen  within  the  cell  walls  after  the  iodin  treatment. 

Starch  is  nearly  always  present  in  the  apple  and  some 
other  fruits,  so  unless  it  is  present  in  jelly  and  such  products 
in  considerable  quantity  it  is  not  likely  that  it  was  added. 

GELATIN 
In  Jellies 
Henzold  Test.  —  Add  water  to  some  of  the  jelly  and  boil 
for  a  short  time,  filter  and  treat  the  filtrate  with  an  excess 


FRUITS  AND  FRUIT  PRODUCTS  41 

of  a  10  per  cent  solution  of  potassium  bichromate  and  boil 
again.  After  cooling  add  2  or  3  drops  of  concentrated 
sulfuric  acid.  A  white  flocculent  precipitate  forms  if 
gelatin  is  present,  and  it  gradually  collects  in  a  lump  at  the 
bottom. 

E.  Beckmann's  Method.  —  Treat  the  jelly  with  95  per 
cent  alcohol  and  wash  the  precipitate  with  alcohol  to  free 
it  from  the  sugar,  then  drive  off  the  alcohol  by  heating. 
Add  a  very  little  water  to  the  residue  and  neutralize  the 
extract  with  calcium  carbonate.  Then  add  formalin  and 
evaporate  to  dryness.  By  this  treatment  gelatin  is  ren- 
dered insoluble. 

Pure  fruit  jellies  have  only  i  to  2  per  cent  of  insoluble 
precipitate,  while  those  jellies  in  which  gelatin  is  used  have 
70  to  86  per  cent  of  insoluble  precipitate. 

AGAR  AGAR 

Boil  the  sample  with  5  per  cent  sulfuric  acid.  Add  a 
crystal  or  two  of  potassium  permanganate,  and  wait  till  it 
settles,  and  examine  the  sediment  for  diatoms  with  a  micro- 
scope.   Their  presence  shows  the  use  of  agar. 

HEAVY  METALS 

Tin,  Zinc,  Lead,  and  Copper 

A.  H.  Allen's  Method.  —  (See  test  for  heavy  metals 
under  canned  meat.) 

ARSENIC 

Marshes  Test.  —  Fit  a  100  cc.  flask  with  a  two-holed 
rubber  stopper,  through  which  passes  a  long-stemmed 
separatory  funnel  reaching  nearly  to  the  bottom,  and  a 


42 


PURE  FOOD  TESTS 


delivery  tube  which  connects  with  a  bulb  tube  containing 
a  little  acetate  of  lead  solution.  This  in  turn  is  connected 
with  a  calcium  chlorid  tube  and  this  with  a  small,  hard 
glass  tube,  15  or  20  cm.  long,  not  over  0.5  cm.  bore,  and 
drawn  to  small  size  in  the  middle.  The  large  part  next  the 
chlorid  tube  is  protected  by  fine  wire  gauze  which  extends 
to  within  a  half  inch  of  the  constricted  part.  Two  burners 
may  be  so  placed  as  to  heat  the  gauze.  The  flask  should 
be  placed  in  water  and  the  bulb  tube  may  be.  Four  grams 
of  arsenic-free  zinc,  and  40  cc.  of  dilute  pure  sulfuric  acid 


TTt= 


Y!S Tf 


.i         =.^^b      t^^ 


Apparatus  for  Marsh  Test 


(i  to  8)  are  placed  in  the  flask.  Let  the  hydrogen  flow  at 
least  a  quarter  of  an  hour,  then  heat  the  gauze  for  15  or  20 
minutes.  There  should  be  no  deposit  in  the  tube.  Now, 
char  a  portion  of  the  sample,  dissolve  in  water  and  pour 
into  the  separatory  funnel,  letting  it  run  slowly  into  the 
flask.  A  dark  deposit  in  the  glass  tube  shows  that  arsenic 
is  present,  but  if  after  an  hour  no  darkening  takes  place  it  is 
quite  safe  to  say  that  no  arsenic  is  present  in  the  fruit. 

GutzeiVs  Test.  —  Place  a  gram  of  pure  zinc,  5  cc.  of 
dilute  sulfuric  acid  (6  per  cent)  and  about  i  cc.  of  a  solution 


FRUITS  AND  FRUIT  PRODUCTS  43 

of  the  sample  in  a  deep  test  tube.  Cover  the  tube  with 
three  thicknesses  of  filter  paper,  fitted  tightly  over  the 
mouth  of  the  tube.  Place  on  the  upper  paper  a  drop  of 
strong  silver  nitrate  solution.  Place  the  tube  in  a  dark 
place  and  leave  for  10  minutes.  If  a  bright  yellow  stain 
forms  on  the  filter  paper,  and  turns  black  or  brown  when 
water  is  added  to  it,  arsenic  is  present.  Unless  one  is 
certain  of  the  purity  of  the  reagents  used  it  is  advisable  to 
make  a  blank  test,  using  distilled  water  instead  of  the  fruit. 

Oxidize  all  sulfids  to  sulfates  before  applying  the  above 
test.  To  find  out  whether  they  are  present  or  not,  sub- 
stitute lead  acetate  for  the  silver  nitrate  on  the  filter  paper. 
To  avoid  some  of  these  difl&culties  treat  according  to  the 
following  method: 

Preparation  of  the  sample  according  to  Leach.  —  If  pos- 
sible reduce  the  sample  to  a  dry  char  by  treatment  with 
concentrated  nitric  and  sulfuric  acids  so  that  it  may  be 
powdered  in  a  mortar.  Dissolve  out  the  arsenic  by  re- 
peated treatment  with  boiling  water.  Save  this  extract, 
and,  when  cool,  filter  and  submit  to  Marsh's  test  which  is 
given  above. 

In  case  the  sample  is  too  much  of  a  solid  to  get  the  arsenic 
out  by  the  above  treatment,  it  may  be  prepared  according 
to  the  directions  of  Chittenden  and  Donaldson:  Heat  100 
grams  of  the  macerated  sample  with  23  cc.  of  pure,  strong 
nitric  acid  to  a  temperature  of  150°  C.  or  160°  C.  Assist 
the  action  by  stirring  occasionally.  When  the  fruit  becomes 
a  deep  yellow  or  orange  color,  remove  the  heat  and  add 
3  cc.  of  pure,  strong  sulfuric  acid.  It  should  be  stirred 
while  nitrous  fumes  are  passing  off.  Heat  again  to  about 
180°  C,  and  before  it  cools  add,  drop  by  drop,  8  cc.  of  pure 
concentrated  nitric  acid.    It  should  be  stirred  constantly 


44  PURE  FOOD  TESTS 

while  the  acid  is  being  added.  Heat  at  200°  C.  till  sulfuric 
acid  fumes  begin  to  come  ofiF  and  only  a  dry  mass  remains. 
Powder  the  mass  and  exhaust  it  with  boiling  water,  filter 
and  test  the  solution  when  cold  with  Marsh's  test. 


CHAPTER  VII 

FLAVORING  EXTRACTS 

LEMON    EXTRACT 

The  important  ingredients  of  lemon  extract  are  lemon  oil 
and  citral,  its  aromatic  constituent.  Oil  of  citronella  and 
oil  of  lemon  grass  are  sometimes  substituted  for  lemon  oil. 
Methyl  alcohol  is  sometimes  used  in  place  of  the  more 
expensive  spirit  alcohol  as  a  solvent  for  the  lemon  oil. 

Lemon  Oil 

The  presence  of  lemon  oil  may  be  detected  by  adding  a 
large  excess  of  water  to  a  small  amount  of  the  extract  in  a 
test  tube.  If  the  mixture  does  not  show  some  cloudiness, 
it  is  a  strong  indication  that  no  lemon  oil  is  present.  The 
degree  of  cloudiness  gives  an  idea  of  the  amount  of  oil 
present. 

Citral 

This  is  present  in  the  oil  of  lemon  grass,  which  is  some- 
times used  as  a  substitute  for  lemon  oil.  Citral  may  be 
detected  by  the  following  test  by  Burgess: 

Add  20  cc.  of  sulfuric  acid  to  85  cc.  of  water.  Dissolve 
in  this  mixture  10  grams  of  mercuric  sulfate.  Shake  2  cc. 
of  the  sample  with  5  cc.  of  this  reagent  in  a  test  tube.  If 
citral  is  present,  the  liquid  will  be  bright  red,  and  will 

45 


46  PURE  FOOD  TESTS 

quickly  disappear  and  give  place  to  a  whitish  compound, 
which  floats  on  top. 

Oil  of  Citronella 

This  is  often  substituted  for  lemon  oil.  It  may  be  de- 
tected by  the  same  test  which  was  used  for  citral.  Instead 
of  the  red  color  and  the  white  compound,  citronella  gives  a 
bright  yellow  color,  which  does  not  disappear  for  some  time. 

Tartaric  or  Citric  Acid 

Precipitate  the  oil  by  the  addition  of  an  equal  volume  of 
water.  Filter  and  add  a  very  little  of  the  filtrate  to  a  test 
tube  nearly  full  of  cold  lime  water.  A  precipitate  wiU 
form  if  tartaric  acid  is  present  and  it  will  dissolve  in  an 
excess  of  ammonium  chlorid  or  acetic  acid.  Filter,  or,  in 
case  no  precipitate  forms,  heat  the  liquid.  Citric  acid  is 
precipitated  in  the  presence  of  a  large  excess  of  hot  lime 
water. 

Methyl  Alcohol 

Mullikin  and  Scudder.  —  Take  2  ft.  of  No.  12-15  copper 
wire  and  bend  at  right  angles  about  8  or  10  inches  from  one 
end.  Grasp  this  bent  end  and  an  ordinary  lead  pencil 
side  by  side  in  such  a  way  that  the  bend  will  be  about  the 
middle  of  the  pencil.  Wind  the  wire  around  the  pencil 
and  toward  the  free  end  of  the  short  part  of  the  wire  until 
you  have  a  coil  3  or  4  cm.  long.  Remove  the  pencil  and 
twist  the  unwound  parts  together  for  a  handle  for  the  coil. 

Dilute  a  portion  of  the  sample  3  or  4  times,  and  oxidize 
lo  cc.  of  the  diluted  liquid  (preferably  in  a  test  tube)  by 
heating  to  a  red  heat  the  above  copper  coil  in  the  oxidizing 
flame  of  a  Bunsen  lamp.  Thrust  the  heated  coil  quickly 
into  the  liquid  contained  in  the  test  tube.    In  a  second 


FLAVORING  EXTRACTS  47 

withdraw  and  immerse  in  water.  Continue  this  operation 
till  the  oxid  of  copper  fails  to  be  reduced  (usually  4  or  5 
times  is  sufficient).  Cool  the  liquid  by  immersing  the  tube 
in  water.  Separate  into  two  parts  and  test  each  for  formal- 
dehyde by  the  following  methods: 

Mullikin,  S.  P.  —  Place  one  of  these  parts  in  an  evap- 
orating dish,  and  add  to  it  i  cc.  of  strong  ammonia,  boil 
gently  over  the  free  flame  till  the  vapors  cease  to  smell  of 
ammonia.  Add  2  or  3  drops  of  strong  hydrochloric  acid 
and  heat  just  to  boiling,  and  cool  quickly  by  dipping  the 
dish  in  cold  water.  Make  the  test  for  formaldehyde:  Add 
a  drop  of  a  solution  of  resorcin  (i:  200)  and  pour  this  mix- 
ture slowly  down  the  side  of  an  inclined  test  tube  wliich 
contains  3  cc.  of  strong  sulfuric  acid,  taking  care  to  keep 
the  liquids  separate.  After  3  minutes  give  the  tube  a  rotary 
motion  by  rolling  between  the  hands  for  a  minute  or  more 
but  only  gradually  mixing  the  water  and  acid,  but  mixing 
only  about  half  of  the  acid. 

Flecks  of  a  rose-red  color  form  if  methyl  alcohol  is  present. 
Bands  of  color  or  flecks  of  other  colors,  even  though  they 
be  tinged  with  red  or  a  rose-red  solution  without  the  pre- 
cipitate, should  never  be  taken  as  proof  that  methyl  alcohol 
is  present.  These  conditions,  however,  are  good  grounds 
for  repeating  the  test;  10  per  cent  or  even  less  may  be  de- 
tected by  this  test. 

Hydrochloric  Acid  and  Ferric  Chlorid  Test.  —  Add  a  few 
drops  of  the  other  part  of  the  above  oxidized  liquid  to  about 
10  cc.  of  milk,  known  to  be  free  from  formaldehyde,  in  a 
porcelain  casserole,  and  add  10  cc.  of  commercial  hydro- 
chloric acid  (sp.  gr.  1.2)  which  contains  i  cc.  of  10  per  cent 
ferric  chlorid  per  500  cc.  Heat  slowly  over  the  open  flame 
nearly  to  boiling.     Give  the  liquid  a  rotary  motion  to  break 


48  PURE  FOOD  TESTS 

up  the  curd.  If  formaldehyde  is  present,  the  liquid  will 
be  colored  violet.  If  not,  it  slowly  turns  brown.  The 
presence  of  formaldehyde  proves  that  methyl  alcohol  was 
in  the  original  extract. 

Coloring  Matter 

Preliminary  Test.  —  Treat  the  sample  with  strong  hydro- 
chloric acid,  and  if  tropaeolin  or  methyl  orange  be  present  the 
solution  will  turn  pink;  Martins  yellow  partially  decolor- 
izes the  solution;  dinitrocresols  decolorizes  the  solution. 
Turmeric  or  naphthol  yellow  produces  no  color  change. 

Turmeric 

Turmeric  may  be  detected  by  soaking  a  piece  of  filter 
paper  in  the  sample,  drying  and  dipping  it  in  a  dilute  solu- 
tion of  boric  acid  or  borax  which  has  been  slightly  acidu- 
lated with  hydrochlorid  acid.  Dry  again  and  a  cherry-red 
color  forms  if  turmeric  is  present.  Add  a  drop  of  dilute 
alkali  and  if  turmeric  be  present  the  paper  will  be  colored 
dark  olive. 

Coal-Tar  Colors 

Evaporate  some  of  the  extract  to  dryness;  take  up  the 
residue  with  water  and  extract  the  coal-tar  colors  if  present, 
and  test  for  them  by  the  method  given  under  canned  vege- 
tables. 

VANILLA  EXTRACTS 

The  best  grades  of  vanilla  extract  are  made  by  treating 
vanilla  beans  with  50  per  cent  alcohol.  Coumarin,  an 
extract  from  tonka  beans,  may  be  used  in  making  the  ex- 
tract. This  of  course  would  make  a  cheaper  product.  If 
less  than  50  per  cent  alcohol  is  used  in  making  the  extract, 
some  alkali  must  be  added  to  dissolve  the  resins  which  will 


FLAVORING  EXTRACTS  49 

not  dissolve  in  a  weaker  alcohol.    In  artificial  extracts  some 
such  coloring  matter  as  caramel  or  tannin  is  used. 

Preliminary  Test.  —  To  a  portion  of  the  extract  add  a 
few  drops  of  lead  acetate  solution.  The  absence  of  a  bulky 
flocculent  precipitate  shows  the  extract  not  to  be  of  high 
quality.  Leach  recommends  that  normal  acetate  of  lead 
be  added  to  the  sample,  and  if  a  precipitate  does  not  form 
it  is  conclusive  evidence  that  it  is  not  a  pure  extract. 

When  a  precipitate  forms  with  the  above  reagent,  it 
should  settle  immediately  and  leave  a  clear  and  almost 
colorless  liquid.  When  there  is  a  mere  cloudiness  only,  it 
may  be  due  to  caramel,  in  which  case  the  extract  is  to  be 
suspected. 

Alkali 

Shake  a  portion  of  the  sample  with  twice  its  volume  of 
water.  If  no  precipitate  forms,  an  alkali  is  present.  A 
flocculent  reddish-brown  precipitate  shows  no  alkali  is 
present.  If  the  solution  is  milky  it  indicates  the  presence 
of  a  foreign  resin. 

Add  hydrochloric  acid  drop  by  drop  to  the  diluted  extract. 
Nothing  more  than  a  mere  turbidity  should  result.  Should 
it  be  quite  turbid  and  the  color  fading  after  a  time,  it  shows 
that  an  alkali  has  been  used. 

Foreign  Resins 

Mix  a  portion  of  the  extract  slowly  with  twice  its  volume 
of  water,  frequently  shaking  the  mixture.  When  this 
solution  is  milky,  it  indicates  a  foreign  resin. 

Hess'  Test.  —  Dealcoholize  25  cc.  of  the  sample  by  con- 
centrating on  the  water-bath,  adding  water  from  time  to 
time  to  retain  the  original  volume.  When  no  alkali  is 
present  in  the  extract,  pure  vanilla  resin  will  be  thrown 


so  PURE  FOOD  TESTS 

down  as  a  reddish-brown  flocculent  precipitate.  Collect 
the  resin,  whatever  its  color,  on  a  filter,  and  wash.  Save 
the  filtrate  to  test  for  caramel.  Place  a  piece  of  the  paper 
and  resin  in  a  dilute  solution  of  potassium  hydroxid.  If  the 
resin  is  that  of  pure  vanilla  it  will  dissolve,  giving  a  deep- 
red  color,  and  is  reprecipitated  when  the  alkali  is  neutralized 
with  hydrochloric  acid.  Dissolve  another  part  of  the 
precipitate  in  alcohol,  and  to  a  part  of  this  solution  add 
a  few  drops  of  ferric  chlorid;  and  to  the  other  part,  hydro- 
chloric acid.  There  should  be  no  marked  coloration  in 
either  case  if  the  resin  is  that  of  pure  vanilla.  Foreign 
resins  nearly  always  produce  a  coloration. 

Caramel 

Shake  the  bottle  of  vanilla,  and  if  the  bubbles,  which 
form,  are  a  bright  caramel  color,  keeping  the  color  till  all 
are  gone,  the  presence  of  caramel  is  indicated. 

Concentrate  a  portion  of  the  filtrate,  which  was  saved  in 
making  the  test  for  foreign  resins,  at  a  rather  low  temper- 
ature until  it  has  about  the  same  color  as  the  original  extract. 
Add  a  few  drops  of  strong  hydrochloric  acid  and  heat  very 
gently.  If  caramel  is  present,  a  yellowish-red  flocculent 
precipitate  will  form.  After  the  liquid  cools,  filter  and 
wash  with  water.  Should  this  precipitate  contain  caramel, 
it  will  not  dissolve  in  water,  ether,  and  alcohol,  but  will 
dissolve  in  sodium  hydroxid,  dilute  alcohol,  and  glacial 
acetic  acid. 

Tannin 

Test  another  portion  of  the  filtrate  made  in  testing  for 
foreign  resins,  with  a  few  drops  of  a  solution  of  gelatin.  A 
slight  precipitate  only  should  form  due  to  the  presence  of  a 


FLAVORING  EXTRACTS  51 

small  amount  of  tannin  normally  present  in  this  filtrate. 
A  large  excess  shows  that  it  has  been  added  to  the  extract. 

COUMARIN 

Leach's  Test.  —  Dealcoholize  a  portion  of  the  sample  as 
above  and  treat  with  ammonia,  add  3  or  4  volumes  of 
chloroform  in  a  separatory  funnel.  Evaporate  the  chloro- 
form extract  in  an  oven,  not  permitting  the  temperature  to 
rise  above  60°  C.  To  the  residue  add  a  few  drops  of  water; 
warm  gently,  and  add  a  little  of  a  solution  of  i  gram  of  crys- 
tallized potassium  iodid  in  50  cc.  of  water,  and  the  solution 
saturated  with  iodin.  If  coumarin  is  present,  a  brown, 
precipitate  will  form,  and  if  stirred  with  a  rod  it  will  collect 
in  dark  green  flecks. 


CHAPTER  VIII 

SACCHARINE  PRODUCTS 
HONEY 

Bees  are  sometimes  fed  with  cane  sugar.  Often  glucose 
syrup  is  poured  over  honeycomb  from  which  the  honey  has 
been  extracted,  and  the  mixture  sold  as  genuine  honey. 

Gelatin  may  be  added  to  increase  the  weight  or  to  thicken 
the  more  voluble  adulterants. 

The  ash  of  genuine  honey  is  not  over  0.3  per  cent.  When- 
ever the  ash  is  greater  than  this  it  should  be  tested  for 
calcium  sulfate,  the  presence  of  a  considerable  quantity  of 
which  is  an  almost  certain  proof  that  starch  glucose  or 
invert  suger  has  been  added  to  the  honey.  Sulfates  may 
be  detected  by  adding  barium  chlorid  to  the  aqueous  solu- 
tion of  the  honey  and  precipitating  barium  sulfate. 

If  the  ash  is  high  and  considerable  chlorids  are  present, 
molasses  has  quite  probably  been  added  to  the  honey.  The 
presence  of  chlorids  may  be  determined  by  the  addition  of 
silver  nitrate  which  precipitates  silver  chlorid. 

CANE  SUGAR 

The  presence  of  cane  sugar  can  be  detected  with  certainty 
only  by  the  use  of  the  polarimeter.  Its  presence  in  large 
quantity  gives  a  high  right-handed  rotation. 

52 


SACCHARINE  PRODUCTS  53 

COMMERCIAL  GLUCOSE  SYRUP 

Allen's  Test.  —  Make  the  test  for  dextrine  which  is 
present  in  commercial  glucose,  but  not  in  pure  honey. 
Dilute  a  portion  of  the  honey  with  an  equal  volume  of  water 
and  add  methyl  alcohol  with  constant  stirring  imtil  there  is 
a  permanent  turbidity.  If  glucose  syrup  is  present  a  heavy 
gummy  precipitate  will  soon  form.  Genuine  honey  gives 
only  a  slight  milkiness. 

GELATIN 

Dilute  a  portion  of  the  sample  and  add  a  solution  of 
tannic  acid.     A  precipitate  indicates  the  presence  of  gelatin. 

Treat  the  sample  with  alcohol,  and  gelatin,  if  present, 
will  be  left  undissolved,  and  it  will  give  its  characteristic 
odor  on  ignition. 

MAPLE  SYRUP 

This  is  sometimes  adulterated  with  glucose,  molasses, 
golden  syrup,  and  with  ordinary  white  sugar.  There  are  no 
satisfactory  simple  chemical  tests  for  these  substances. 

Pure  maple  syrup  should  have  an  ash  not  lower  than 
0.35  to  0.40  per  cent.  A  lower  ash  shows  that  cane  sugar 
has  been  added.  A  higher  ash  would  indicate  the  presence 
of  molasses  or  brown  sugar  stock.  These  last  two  adul- 
terants, if  present  in  great  abundance,  may  be  detected  by 
taste. 

Glucose 

This  may  be  detected  by  the  use  of  the  polarimeter.  Pure 
maple  syrup  gives  53.1  to  60  direct,  and  —  22.2  to  —  21.9 
after  hydrolysis.  Maple  syrup  adulterated  with  glucose 
gives  80  to  100  direct  and  18.9  to  45.6  after  hydrolysis 
(according  to  Ogdon). 


CHAPTER   IX 

SPICES 
MUSTARD 

Mustard  is  often  adulterated  with  mustard  hulls,  wheat, 
and  rice.  And  when  white-colored  flour  of  any  kind  is 
used,  turmeric,  Martius  yellow,  or  a  coal-tar  color  is  em- 
ployed to  give  the  mixture  the  color  of  mustard.  Cayenne 
pepper  is  occasionally  used  to  impart  pungency  to  diluted 
mustard. 

FLOUR 

Boil  2  grams  of  the  mustard  in  4  or  5  cc.  of  distilled  water 
for  about  10  minutes.  After  it  is  cool,  add  a  few  drops  of 
iodin  solution  slowly,  avoiding  a  large  excess  though  having 
a  little  uncombined  iodin.  If  a  blue  color  is  produced, 
some  starchy  matter  has  been  added  to  the  mustard.  The 
intensity  of  the  reaction  is  an  indication  of  the  amount  of 
starchy  matter  used.  Pure  mustard  contains  no  starch 
and  hence  gives  no  reaction  with  iodin. 

COLORING  MATTER 

Pure  mustard  is  a  very  light  dull  yellow,  and  whenever 
the  sample  is  bright  yellow,  there  is  good  grounds  for  sus- 
pecting the  presence  of  some  artificial  coloring  matter. 

54 


SPICES  5S 

Turmeric 

Add  strong  ammonium  hydroxid  to  the  mustard,  and  if 
turmeric  is  present  an  orange-red  color  is  usually  produced. 

Make  an  alcoholic  extract  of  the  sample  and  dip  a  piece 
of  filter  paper  in  it,  and  when  dry  draw  it  through  a  cold, 
saturated  solution  of  boric  acid  in  water.  An  orange  or 
red-brown  tint  produced  on  the  paper  indicates  the  pres- 
ence of  turmeric. 

Thoroughly  mix  2  or  3  grams  of  the  mustard  with  castor 
oil  and  filter.  If  turmeric  is  present  the  filtrate  will  appear 
fluorescent. 

Extract  a  portion  of  the  sample  with  3  times  its  weight 
of  wood  alcohol  and  filter.  Evaporate  one  half  of  the  solu- 
tion to  dryness  and  add  a  little  hydrochloric  acid  to  the 
residue.  This  will  turn  red  whenever  turmeric  is  present, 
and  if  an  excess  of  alkali  be  added  it  will  change  to  a  greenish 
blue.  Evaporate  the  other  half  to  dryness  and  moisten 
with  a  solution  of  boric  acid  and  dry  on  a  steam  bath.  A 
cherry-red  color  indicates  turmeric. 

Martius  Yellow  or  Analogous  Coal-Tar  Coloring 

Matter 

Extract  the  slightly  acidified  sample  with  95  per  cent 
alcohol  and  dye  wool  as  directed  under  "Vegetables." 
The  wool  will  be  dyed  a  bright  yellow. 

Allen's  Test.  —  Treat  a  portion  of  the  sample  with  cold 
alcohol,  and  shake  vigorously  for  5  minutes,  then  filter  and 
evaporate  the  filtrate  to  dryness;  add  enough  water  to  take 
up  the  residue  and  dye  some  white  wool  in  this  liquid  as  in 
the  last  test.  When  the  dyed  wool  is  wrapped  in  white 
paper  and  heated  to  120°  in  an  air  bath,  part  of  the  coloring 


S6  PURE  FOOD  TESTS 

matter  will  be  transferred  to  the  paper.  The  coloring 
matter  dissolves  readily  in  dilute  ammonia  or  hot  water, 
and  on  the  addition  of  hydrochloric  acid  the  solution  is 
decolorized  and  a  yellow  precipitate  formed.  This  distin- 
guishes it  from  picric  acid. 

Cayenne  Pepper 

Allen's  Test.  —  Boil  i  gram  of  the  mustard  for  a  few 
minutes  with  alcohol,  filter,  and  evaporate  to  dryness  at 
about  ioo°.  Taste  the  residue  and  cayenne  may  be  recog- 
nized by  its  pungency.  Or  heat  a  portion  of  the  extract, 
and  smell  the  fumes.  Irritation  of  the  lungs  and  coughing 
will  siwely  follow  if  cayenne  pepper  is  present. 

PEPPER 

Pepper  may  be  adulterated  with  wheat,  buckwheat, 
pepper  husks,  ground  olive  stones,  spent  ginger.  Cayenne 
pepper  is  sometimes  added  to  adulterated  pepper  to  give  it 
the  normal  pungency.  Many  of  these  adulterants  can  be 
detected  only  by  the  aid  of  the  microscope. 

Neuss's  Test.  —  True  pepper  turns  an  intense  yellow 
when  covered  with  strong  hydrochloric  acid.  Any  adul- 
teration can  be  detected  at  once  by  the  color. 

Ground  Olive  Stones  or  "Poivrette" 

Make  a  paste  of  the  pepper  with  caustic  alkali.  Dilute 
with  a  large  quantity  of  water  and  wash  by  decantation. 
Olive  stones  will  be  colored  a  bright  yellow;  pepper-husks 
will  appear  dark. 

Jumeau's  Test.  —  Dissolve  5  grams  of  iodin  in  a  mixture 
of  50  cc.  of  ether  and  50  cc.  of  alcohol.  Cover  the  bottom 
of  a  porcelain  capsule  with  the  finely  ground  pepper,  and 


SPICES  57 

add  just  enough  of  the  iodin  mixture  to  wet  the  entire  mass, 
and  mix  well  till  it  has  the  same  consistency  throughout. 
Let  dry  in  the  air,  then  powder  and  examine  it,  and  if  olive 
stones  are  present  they  will  be  colored  yellow.  Pure 
pepper  would  have  a  deep  brown  color. 

Aniline  acetate,  one  part  aniline  in  3  parts  acetic  acid, 
colors  pure  pepper  gray  or  white  and  olive  stones  yellowish 
brown. 

Cayenne 

Heat  some  of  the  red  particles  found  in  the  pepper  and 
their  characteristic  vapor  is  produced.  Dissolve  the  par- 
ticles in  alcohol  or  ether  and  the  same  vapors  are  produced. 


CHAPTER  X 

VINEGAR 

Vinegars  may  be  adulterated  by  the  addition  of  mineral 
acids  as  sulfuric  or  hydrochloric.  Caramel  or  the  coal-tar 
dyes  may  be  employed  to  improve  the  color  or  to  give  color 
to  an  artificial  product.  Malic  acid  is  always  present  in 
cider  vinegar.  Potassium  acid  tartrate  occurs  in  true  wine 
vinegar.  Poisonous  metals  may  be  present  in  vinegars 
containing  free  mineral  acid.  Entirely  artificial  cider 
vinegar  is  often  found  on  the  market. 

Preparation  of  the  Sample  for  Testing 

If  the  vinegar  is  turbid  from  any  suspended  matter,  it 
should  be  filtered.  The  samples  should  be  analyzed  at 
once,  and  in  the  laboratory  they  should  always  be  kept  in 
glass-stoppered  bottles. 

General  Observations.  —  Ignite  a  little  of  the  vinegar 
residue  on  a  clean  platinum  wire  in  a  colorless  Bunsen 
flame,  and  if  it  is  pure  cider  vinegar  the  flame  will  be 
colored  the  characteristic  lilac  color  of  potassium.  The 
sodium  flame  is  absent  or  only  a  mere  trace  of  it  is  present. 
But  in  all  artificially  colored  vinegars,  spirit  sugar  and 
glucose  vinegars,  the  sodium  flame  predominates. 

The  residue  of  cider  vinegar  is  thick,  viscid,  or  mucilag- 
inous, of  a  light  brown  color,  astringent  acid  taste  though 
not  unpleasant.    The  solids  of  sugar-house  vinegar,  those 

S8 


VINEGAR  59 

from  colored  spirit  and  wood  vinegar,  each  have  a  bitter 
taste  on  account  of  the  caramel  used  to  color  them.  The 
residue  of  the  sugar-house  vinegar  has  the  odor  of  molasses. 
Wood  vinegar  when  present  gives  a  residue  with  a  tarry  or 
smoky  taste  and  smell.  Glucose  vinegar  gives  the  odor 
of  scorched  com.  Solids  of  fruit  vinegars  are  quite  soluble 
in  alcohol,  except  a  granular  residue  in  grape  vinegar, 
while  the  soUds  of  malt  and  glucose  vinegars  are  almost 
insoluble. 

The  ash  of  fruit  vinegars  and  malt  vinegars  has  a 
distinct  alkaUne  reaction,  while  that  of  spirit  and  wood 
vinegars  is  very  feebly  alkaline. 

CIDER  VINEGAR 

To  lo  cc.  of  the  vinegar  add  a  few  drops  of  neutral  lead 
acetate  solution.  If  the  sample  is  cider  vinegar  a  pre- 
cipitate will  form. 

FREE  MINERAL  ACIDS 

The  ash  of  pure  cider  vinegar  is  always  alkaline.  If  a 
vinegar  should  show  a  neutral  reaction  this  would  cer- 
tainly indicate  the  presence  of  a  free  mineral  acid.  If  the 
ash  be  alkaline,  no  acid  except  nitric  could  have  been 
present,  and  this  is  seldom,  if  ever,  used  as  an  adulterant 
of  vinegar. 

Methyl  Violet  Test.  —  Dilute  5  cc.  of  the  vinegar  with  an 
equal  amount  of  water,  and  mix  thoroughly.  Add  4  or 
5  drops  of  methyl  violet  solution  made  by  putting  one 
part  of  methyl  violet  2  B.  in  10,000  parts  of  water.  A 
blue  or  green  color  indicates  the  presence  of  free  mineral 
adds. 


6o  PURE  FOOD  TESTS 

When  the  Ash  is  Alkaline  Apply 

Ashby^s  Test.  —  Extract  0.5  gram  of  logwood  in  100 
cc.  of  water  and  dry  a  drop  or  two  on  a  porcelain  surface. 
Then  add  a  drop  of  the  vinegar  and  dry  again.  If  the 
residue  is  red,  a  mineral  acid  is  present;  if  yellow,  mineral 
acids  are  absent.  When  only  a  very  small  amount  of  the 
acid  is  present  the  red  coloration  will  be  destroyed  on 
diluting  with  water,  but  may  be  restored  by  concentrating 
the  liquid. 

Sulfuric  Acid 

Sulfuric  acid,  if  present,  will  cause  the  vinegar  to  leave 
a  charred  mass  when  evaporated  over  the  water-bath. 

Frear's  Method.  —  Mix  5  cc.  of  the  sample  and  5  or 
10  cc.  of  water,  and  add  a  very  little  of  a  solution  of 
methyl  violet  (made  by  dissolving  one  part  of  methyl 
violet  2  B,  in  100,000  parts  of  water).  A  blue  or  green 
coloration  shows  the  presence  of  mineral  acids. 

Sulfuric  Acid  as  Distinguished  from  Sulphates 

Allen's  Method.  —  Evaporate  100  cc.  of  the  vinegar 
down  to  one  tenth  its  volume,  and  when  cold  add  50  cc. 
of  alcohol.  Sulfuric  acid  remains  in  solution  while  the 
sulfates  are  precipitated.  Dilute  the  solution  and  pre- 
cipitate the  acid  with  barium  chlorid. 

HYDROCHLORIC  ACID 

Free 

Place  a  definite  quantity  of  the  vinegar  in  a  distilling 
flask  and  distil  off  half.    Add  a  few  drops  of  silver  nitrate 


VINEGAR  6i 

to  the  distillate.    If  a  precipitate  forms,  hydrochloric 
acid  is  present. 

MALIC  ACID 

Leach's  Method.  —  To  5  cc.  of  the  sample,  add  a  few 
drops  of  a  solution  of  calcium  chlorid  (i :  10) ;  make  slightly 
alkaline  with  ammonia.  Filter  oflE  any  precipitate  that 
may  form,  add  20  to  30  cc.  of  95  per  cent  alcohol  to  the 
filtrate  and  heat  to  boihng.  If  malic  acid  is  present,  a 
voluminous  flocculent  precipitate  will  form.  A  precipitate 
may  form  in  vinegars  containing  dextrin.  Make  a  further 
test  for  mahc  acid  by  the  following:  Filter  and  treat  the 
precipitate  with  a  little  alcohol,  and  when  dry  add  con- 
centrated nitric  acid  and  evaporate  to  dryness  on  a  water- 
bath.  Treat  the  residue  with  sodium  carbonate,  boil  for  a 
short  time,  filter.  Add  acetic  acid  to  the  filtrate  till 
slightly  alkaline,  boil  till  carbon  dioxid  is  expelled,  and  if 
on  the  addition  of  calcium  sulfate  a  precipitate  forms, 
it  indicates  the  presence  of  malic  acid. 

COLORING  MATTER 
Caramel 

The  residue  of  vinegar  to  which  much  caramel  has  been 
added  has  an  unusually  dark  color  and  bitter  taste. 

Crampton  and  Simons'  Method.  —  Shake  well  together 
in  a  corked  flask  50  cc.  of  the  vinegar  with  about  half  as 
many  grams  of  fuller's  earth;  after  standing  for  half  an 
hour  filter.  Vinegar  containing  no  artificial  color  will 
show  scarcely  any  change  in  color  when  thus  treated.  A 
caramel-colored  vinegar  will  be  decolorized  in  proportion 
to  the  amount  of  caramel  present. 


6a  PURE  FOOD  TESTS 

Coal-tar  Colors  in  Wine  Vinegar 

Test  by  the  usual  test  for  coal-tar  dyes.  See  under 
canned  vegetables. 

METALLIC  IMPURITIES 

Vinegars  containing  free  mineral  acids  are  sometimes 
found  to  contain  poisonous  metals. 

Evaporate  200  to  400  cc.  of  the  vinegar  to  dryness,  add 
a  little  sodium  hydroxid  to  this  residue  and  burn  to  an 
ash  over  a  low  flame.  It  may  be  necessary  to  add  a  httle 
potassium  nitrate  once  or  twice.  Add  a  little  dilute 
hydrochloric  acid  and  saturate  with  hydrogen  sulfid  and 
test  for  lead,  zinc,  copper  and  arsenic  according  to  Allen's 
method  given  under  canned  meats. 

Spices  to  Increase  Pungency 

Leach.  —  Neutralize  a  portion  of  the  vinegar  with 
sodium  carbonate.  The  presence  of  spices  is  easily  de- 
tected by  tasting  this  mixture. 

Another  Test.  —  Exactly  neutrahze  a  little  of  the 
vinegar  as  above,  evaporate  to  smaller  bulk  and  taste  as 
before,  then  shake  the  concentrated  liquid  with  ether, 
separate  the  ethereal  layer  and  evaporate  it,  and  taste  the 
residue. 

Tartar  in  Wine  Vinegar 

The  presence  of  tartar  in  vinegar  proves  it  to  be  wine 
vinegar. 

Attends  Method.  —  Evaporate  a  portion  of  the  vinegar 
and  treat  the  residue  with  alcohol;  a  granular  residue  of 


VINEGAR  63 

tartar  remains  undissolved.  To  prove  that  it  is  tartar, 
decant  the  alcohol  and  dissolve  the  residue  in  a  httle  hot 
water,  cool,  rub  the  inside  of  the  vessel  with  a  glass  rod, 
and  if  tartar  was  present  acid  potassium  tartrate  will  be 
deposited  where  the  rod  touched  the  vessel.  The  test 
will  be  more  sensitive  if  an  equal  volume  of  alcohol  is 
added. 

Free  Tartaric  Acid  in  Wine  Vinegar 

Test  as  for  Tartar.  —  Treat  the  alcoholic  solution  of  the 
extract  with  an  alcoholic  solution  of  potassium  acetate. 
Rub  the  sides  of  the  vessel  as  before,  and  if  tartaric  acid 
is  present  the  streaks  and  sometimes  a  precipitate  forms 
where  the  rod  touches  the  vessel. 


GLUCOSE 

Whenever  glucose  is  present  in  a  vinegar,  a  precipitate 
nearly  always  forms  on  the  addition  of  ammonium  oxalate. 


CHAPTER  XI 

FATS  AND  OILS 
LARD 

Lard  is  very  often  adulterated  with  cottonseed  oil, 
cottonseed  stearin  and  beef  stearin.  Their  being  very 
much  cheaper  accounts  for  the  sophistication. 

Cottonseed  Oil 

Halphen's  Test.  —  Dissolve  i  per  cent  of  sulfur  in  a 
given  volume  of  carbon  bisulfid.  Add  an  equal  volume  of 
amylic  alcohol.  Mix  3  to  5  cc.  of  this  reagent  with  an 
equal  volume  of  the  melted  lard  in  a  test  tube.  Close  with 
a  cotton  stopper  and  boil  for  15  minutes  in  a  bath  of  satu- 
rated brine.  The  presence  of  cottonseed  oil  is  indicated 
by  a  deep-red  or  orange  color,  little  or  no  color  resulting  in 
its  absence.  Lard  from  hogs  fed  on  any  of  the  various 
cottonseed  products  may  give  a  faint  reaction  when  this 
test  is  applied. 

Cottonseed  Stearin 

Since  cottonseed  stearin  is  only  the  more  solid  portions 
of  cottonseed  oil,  the  above  test  may  be  applied,  but  to 
distinguish  it  from  the  latter  it  is  necessary  to  make  deter- 
minations quite  beyond  the  scope  of  this  set  of  tests. 

64 


FATS  AND  OILS  65 

Beef-Stearin 

It  is  very  diflScult  to  identify  beef -stearin  by  chemical  tests. 
It  is  usually  detected  by  use  of  the  microscope.  Leach 
gives  the  following  method:  Make  a  solution  of  2  to  5  grams 
of  the  fat  in  10  to  20  cc.  of  ether.  Let  stand  a  half  day, 
at  about  the  room  temperature.  Loosely  stopper  the  tube 
with  cotton  to  prevent  too  rapid  evaporation  of  the  ether. 
It  is  well  to  vary  the  conditions  of  heat,  amount  of  solvent, 
and  rate  of  crystallization,  to  get  the  best  possible  results. 
It  may  often  be  well  to  separate  the  crystals  thus  obtained 
by  filtering  and  recrystallizing  from  ether.  Separate  the 
crystals  that  form  at  the  bottom  of  the  test  tube  from  the 
liquid  portion  by  pouring  on  a  small  filter.  Wash  them 
several  times  with  ether,  but  not  sufficient  to  remove  the 
mother  liquor  entirely.  In  case  it  is  all  removed,  and  the 
crystals  are  too  fragile  to  mount,  add  a  drop  of  alcohol. 
Crystals  of  lard  stearin  are  flat  rhomboidal  plates,  one  end 
being  oblique  to  the  sides,  and  they  do  not  appear  to  be 
regularly  grouped.  Beef-stearin  crystals  are  rod-shaped, 
or  needles  often  apparently  curved  with  pointed  ends,  and 
are  arranged  in  clusters  like  the  ribs  of  a  fan,  the  crystals 
radiating  from  a  common  point.  Under  certain  conditions 
the  lard  crystals  are  not  irregularly  grouped,  but  are  arranged 
like  the  parts  of  a  feather,  where  one  part  seems  attached 
to  another  close  at  hand.  Considerable  experience  is  neces- 
sary to  use  this  test  with  absolute  certainty. 

OLIVE  OIL 

Olive  oil  is  one  of  the  most  commonly  adulterated  foods. 
The  commonest  adulterant  probably  is  cottonseed  oil. 
Other  foreign  oils,  such  as  peanut,  sesame,  and  rape,  are 
sometimes  used. 


66  PURE  FOOD   TESTS 

Preliminary  Test.  —  Pure  olive  oil  turns  from  a  pale  to 
a  dark-green  color  in  a  few  minutes,  when  it  is  shaken  with 
the  same  volume  of  concentrated  nitric  acid  or  sulfuric 
acid.  Whenever  a  reddish  to  an  orange,  or  brown  color- 
ation results,  the  presence  of  a  foreign  vegetable  oil  is  in- 
dicated (probably  a  seed  oil). 

Bach  gives  the  following  results  of  strong  nitric  acid  on 
the  common  oils.  Olive  oil  when  shaken  with  nitric  acid 
gives  a  pale  green,  which  changes  to  an  orange  yellow  after 
heating  five  minutes.  With  similar  treatment  peanut  oil 
gives  pale  rose  and  brownish  yellow;  rape  oil,  pale  rose  and 
orange  yellow;  sesame  oil,  white  and  brownish  yellow; 
sunflower  oil,  dirty  white  and  reddish  yellow;  cottonseed 
oil,  yellowish  brown  and  reddish  brown;  castor  oil,  pale 
rose  and  golden  yellow. 

PonteVs  Test;  Elaiden  Test.  —  Treat  i  cc.  of  mercury 
with  12  cc.  of  cold  nitric  acid  (sp.  gr.  1.42)  and  shake  2  cc. 
of  this  freshly-made  solution  with  50  cc.  of  the  sample  in 
a  bottle  every  10  minutes  for  2  hours.  Oils  which  are 
principally  olein,  or  mixtures  of  olein  and  solid  esters  like 
palmatin  and  stearin,  give  more  or  less  solid  products,  but 
olive  oil  is  remarkable  for  the  firmness  of  the  canary  or 
lemon-yellow  mass  which  is  formed.  After  standing  a  day 
the  mass  cannot  be  pierced  with  a  glass  rod  and  sometimes 
it  gives  forth  a  sound  when  struck. 

This  test  requires  considerable  experience  to  be  used  with 
any  great  degree  of  certainty. 

Cottonseed  Oil 

Carbon  bisulfid  containing  i  per  cent  of  sulfur  in  solu- 
tion is  mixed  with  an  equal  amount  of  amyl  alcohol.  Equal 
volumes  (about  3  cc.  of  this  reagent  and  the  sample,  are 


FATS  AND   OILS  67 

mixed  in  a  test  tube,  which  is  loosely  stoppered  with  cotton, 
and  heated  in  a  bath  of  boiling  saturated  brine  for  a  quarter 
of  an  hour.  The  presence  of  cottonseed  oil  is  shown  by  the 
formation  of  a  deep-red  or  orange  color.  Little  if  any 
color  is  produced  in  its  absence.  If  no  color  is  produced 
it  is  well  to  add  another  cc.  of  the  reagent  and  heat  5  or  10 
minutes  more,  and  to  repeat  this  again  if  no  color  forms. 
Lard  and  lard  oil  from  animals  fed  on  cottonseed  meal 
may  give  a  faint  reaction. 

Peanut  Oil  (Arachis  Oil) 

Bellier's  Test.  —  Saponify  a  gram  of  the  sample  with  5 
cc.  of  a  solution  of  85  grams  potassium  hydroxid  in  a  liter 
of  strong  alcohol.  This  may  be  done  in  a  small  Erlen- 
meyer  flask  on  the  water-bath.  Then  boil  for  two  minutes, 
neutralize  exactly  with  dilute  acetic  acid  (use  phenolphtha- 
lein  as  the  indicator).  Cool  the  mixture  by  placing  the 
flask  in  water  at  17°  to  19°  C.  A  precipitate  usually  forms. 
Add  50  cc.  of  70  per  cent  alcohol  which  contains  one  per 
cent  by  volume  of  concentrated  hydrochloric  acid  (sp.  gr. 
1.2).  Shake  the  flask  vigorously  and  cool  again  as  before. 
If  no  precipitate  forms  the  oil  is  not  adulterated  with  peanut 
oil.  The  presence  of  10  per  cent  or  more  of  peanut  oil 
produces  a  precipitate,  even  a  smaller  amount  will  produce 
a  cloudiness  after  standing  between  17°  and  19°  C.  for  30 
minutes. 

Some  varieties  of  olive  oil  from  Tunis  give  the  same 
turbidity  when  the  70  per  cent  alcohol  is  added.  To  dis- 
tinguish these  from  peanut  oil  heat  the  mixture  on  the 
water-bath  till  everything  has  dissolved,  and  cool  to  17°  to 
19°.  The  cloudiness  will  not  appear  if  the  oil  is  pure,  but 
will  reappear  if  peanut  oil  is  present 


68  PURE  FOOD   TESTS 

Sesame  Oil 

Badouin's  Test.  —  About  o.i  of  a  gram  of  cane  sugar  is 
dissolved  in  lo  cc.  of  hydrochloric  acid  (sp.  gr.  1,20)  shaken 
vigorously  with  20  grams  of  the  sample  for  a  minute  or 
more.  After  standing  for  a  while  the  aqueous  solution  will 
separate  from  the  oil.  If  i  per  cent  or  more  of  sesame  oil 
is  present,  the  aqueous  solution  will  be  colored  crimson. 

Tocher's  Test.  —  Dissolve  i  gram  of  pyrogallic  acid  in 
15  cc.  of  strong  hydrochloric  acid.  Add  an  equal  volume 
of  the  oil  in  a  separatory  funnel.  When  it  has  stood  a 
minute,  draw  off  the  aqueous  solution  and  boil.  In  the 
presence  of  sesame  oil  it  is  colored  red  by  transmitted  light, 
and  blue  by  reflected  light. 

Rape  Oil 

Palas'  Test.  —  Make  a  i  per  cent  solution  of  fuchsin  and 
a  30  per  cent  solution  of  sodium  acid  sulfite.  Mix  together 
20  cc.  of  each  of  these  solutions  and  add  200  cc.  of  water 
and  5  cc.  of  strong  sulfuric  acid.  After  the  solution  is 
decolorized,  10  cc.  of  the  sample  is  shaken  with  it.  If  rape 
oil  is  present,  the  color  will  be  partially  restored.  To 
prevent  the  formation  of  the  color  by  contact  with  the  air 
have  the  vessel  full  of  the  mixture. 


CHAPTER  XII 

BEVERAGES 
COFFEE 

Coffee  is  often  colored  with  such  substances  as  Scheele's 
green,  chrome  yellow,  iron  oxide,  Prussian  blue,  indigo  and 
turmeric.  Imitation  coflfee  beans  have  been  made  of  wheat 
flour,  bran,  rye,  chicory  and  peas. 

Allen's  Preliminary  Test.  —  A  good  preliminary  test  for 
ground  coffee  is  to  sprinkle  some  of  it  on  the  surface  of  cold 
water.  The  oil  of  true  coffee  prevents  the  particles  from 
being  readily  soaked,  and  so  they  float  for  some  time. 
Chicory  and  most  of  the  other  adulterants  of  coffee  contain 
no  oil,  but  do  contain  caramel,  which  is  quickly  extracted 
by  the  water  producing  a  zone  of  brown  color  about  such 
particles.  They  become  soaked  and  quickly  sink.  The 
liquid  containing  pure  coffee  diffuses  uniformly  without 
coloring  the  water  to  any  perceptible  degree.  Chicory  and 
similar  roots  give  a  dark  brown,  turbid  infusion.  Roasted 
cereals  do  not  impart  so  distinct  a  color  to  water. 

Coloring  Matter 

Shake  the  coffee  beans  in  cold  water  and  make  the  regular 
qualitative  tests  for  the  inorganic  coloring  matters  — 
Scheele's  green  may  be  identified  by  testing  for  copper  and 
arsenic;  chrome  yellow,  by  testing  for  lead  chromate;  iron 
oxide  may  be  detected  by  its  characteristic  tests. 

69 


70  PURE   FOOD   TESTS 

Organic  coloring  matter  is  best  extracted  with  alcohol. 
Prussian  blue  may  be  detected  by  dissolving  it  from  the 
sediment  with  hot  caustic  alkali,  acidifying  with  hydro- 
chloric acid,  treating  it  with  a  drop  of  ferric  chlorid.  If 
present,  ferric  ferrocyanide,  a  blue  precipitate,  will  be 
formed.  Indigo  is  not  discharged  by  sodium  hydroxid, 
while  Prussian  blue  is.  It  will  form  a  deep  blue  solution 
with  sulfuric  acid. 

Test  for  turmeric  as  under  mustard. 

Imitation  Coffee  Beans 
Most  imitation  cofifee,  as  already  stated,  is  heavier 
than  water.  Coffee  contains  no  starch,  so  the  imitation 
beans  made  of  cereals  may  be  detected  by  testing  for 
starch.  The  artificial  beans  may  also  be  identified  by 
their  uniformly  regular  form.  Roasted  cereals  are  glossy. 
If  legumes  are  present  pieces  of  hulls  ate  usually  present. 

Starch 
Allen's  Method.  —  Boil  the  coffee  in  lo  parts  of  water. 
When  perfectly  cold  add  to  it  a  little  sulfuric  acid,  then  a 
strong  solution  of  potassium  permanganate,  drop  by 
drop,  with  constant  shaking,  till  the  liquid  is  almost 
decolorized;  strain  or  decant  and  add  to  the  solution  a 
solution  of  iodin.  If  i  per  cent  or  more  of  starch  is 
present  a  blue  coloration  will  be  produced. 

Chicory 
Rimmingtoti's  Test.  —  Boil  a  portion  of  the  sample  with 
water  which  contains  a  little  sodium  carbonate;   decant, 
wash  and  treat  the  residue  with  a  weak  solution  of  bleach- 
ing powder   for   several   hours.    The   solution    will   be 


BEVERAGES  71 

decolorized.    The  coffee  will  be  at  the  bottom  as  a  dark 
layer  while  the  chicory  will  be  a  light  layer  above  it. 

Albert  Smith's  Test.  —  Boil  10  grams  of  the  sample  in 
250  cc.  of  water;  strain  and  add  basic  lead  acetate  in 
slight  excess.  A  precipitate  forms,  and  when  it  has 
settled  the  supernatant  liquid  will  be  colorless  if  the 
coffee  is  pure,  but  more  or  less  colored  if  chicory  is  present. 

TEA 

Tea  is  adulterated  by  the  substitution  of  inferior  grades 
for  those  of  better  quaUty,  by  the  addition  of  exhausted 
leaves  and  foreign  leaves,  by  the  use  of  coloring  matter  or 
"facing"  such  as  Prussian  blue,  indigo  or  turmeric  to 
color  green  tea,  and  sometimes  graphite  to  color  black 
tea.  Foreign  astringents  (generally  catechu)  are  added 
to  conceal  the  presence  of  exhausted  leaves.  An  imitation 
tea,  "lie  tea,"  is  made  of  the  stems  and  dust  with  mineral 
matter,  and  some  starch  or  gum  to  hold  these  together. 

Foreign  Leaves 

Though  there  are  several  chemical  tests  for  foreign 
leaves,  none  are  as  satisfactory  as  a  microscopical  exami- 
nation. Soften  the  leaves  by  soaking  in  hot  water,  unroll 
carefully  and  examine  with  a  hand  lens  or  low  power  of 
the  microscope.  Compare  with  a  genuine  leaf  —  the 
shape,  margin  and  venation. 

Exhausted  Tea  Leaves 

Sometimes  such  leaves  may  be  detected  by  a  physical 
examination.    They  are  often  more  or  less  unrolled  and 


72  PURE  FOOD   TESTS 

"facing"  such  as  Prussian  blue,  indigo  or  turmeric  to 
broken  on  the  edges.  But  the  only  certain  way  of  ascer- 
taining their  presence  is  to  determine  the  soluble  ash 
which  is  from  2.5  to  4  per  cent  in  pure  tea  and  usually  less 
than  0.8  per  cent  in  exhausted  tea. 

Lie  Tea 

This  imitation  tea  is  easily  detected  by  pouring  hot 
water  over  the  leaves.  If  they  are  artificial,  they  will 
break  down  into  the  fragments  of  which  they  were  made. 

Facing 

Organic  coloring  matter  may  be  detected  by  the  same 
method  used  for  detecting  such  colors  in  coffee. 

Catechu 

Hager's  Test.  —  Boil  a  httle  of  the  tea  in  water,  and  add 
to  the  extract  an  excess  of  lead  monoxid.  If  the  tea  is 
pure  the  addition  of  a  solution  of  silver  nitrate  produces 
only  a  sUght  grayish  precipitate,  but  when  catechu  is 
present  a  yellow  flocculent  precipitate  forms. 

A   FEW  OF  THE   BEST   BOOKS  ON   FOOD   ANALYSIS 

Allen,    A.    H.,    Commercial    Organic    Analysis,    1898.     Pub., 

Blakiston,  Phila.     Price,  $29.50. 
Blyth,  a.  W.,  Foods,  their  Composition  and  Analysis,   1903. 

Pub.,  Scribner.     Price,  $8.40. 
Hassall,  a.  H.,  Food,  its  Adulterations  and  the  Methods  for 

their  Detection,  1874.     Longmans,  Green  &  Co. 
Leach,    A.    E.,    Food,    Inspection  and  Analysis,    1905.     Pub., 

John  Wiley  &  Sons,  New  York.     Price,  $7.50. 


CHEMICALS 


73 


Leffmann,  H.  and  Beam,  W.,  Select  Methods  of  Food  Analysis, 

1905.     Pub.,  Blakiston.     Price,  $2.50. 
Olsen,  Pure  Foods  Pub.,  Ginn  &  Co.     Price,  $.80. 
U.  S.  Dept.  of  Agr.,  Bureau  of  Chem. 
Bulletin  107,  Methods  of  Analysis  of  Foods,  1908. 
W11.EY,  Foods  and  their  Adulteration. 

The  following  are  the  chemicals  used  in  making  all  the 
tests  in  this  book.  Most  of  these  are  found  in  every 
chemical  laboratory.  The  more  uncommon  ones  may  be 
obtained  from  Eimer  and  Amend,  205-211  Third  Avenue, 
New  York,  or  from  Bausch  and  Lomb  Optical  Co.,  Roches- 
ter, N.  Y. 

Acetic  acid 

Ammonium  carbonate 

Ammonium  chlorid 

Ammonium  hydroxid 

Ammonium  molybdate 

Ammonium  oxalate 

Ammonium  sulfid 

Amyl  alcohol 

Aniline 

Barium  chlorid 

Barium  peroxid 

Boric  acid 

Bromine 

Calcium  carbonate 

Calcium  chlorid 

Calcium  sulfate 

Cane  sugar 

Carbon  bisulfid 

Castor  oil 

Chloroform 

Diphenylamine 

Ether 

Ethyl  alcohol 


Ferric  chlorid 

Formalin 

Fuchsin 

Gelatin 

Glycerol 

Hydrochloric  acid 

lodin,  tincture  of 

Lead  acetate  (basic) 

Lead  oxide 

Lime  water 

Litmus  paper 

Logwood  chips 

Mercury,  metallic 

Mercury  sulfate 

Methyl  alcohol 

Molybdic  oxid 

Nitric  acid  (sp.  gr.  1.42) 

OxaUc  acid 

Petroleum  spirit 

Phenolphthalein 

Phenylhydrazine  hydrochlorid 

Phosphoric  acid 

Potassium  bichromate 


74 


PURE  FOOD   TESTS 


Potassium  carbonate 
Potassium  chromate 
Potassium  ferrocyanid 
Potassium  hydroxid 
Potassium  iodate 
Potassium  iodid 
Potassium  nitrate 
Potassium  permanganate 
Pyrogallic  acid 
Rennet,  standard  extract 
Resorcin 
Silver  nitrate 


Sodium  acetate 
Sodium  acid  sulfite 
Sodium  carbonate 
Sodium  chlorid 
Sodium  hydroxid 
Starch 
Sulfur 

Sulfuric  acid 
Tannic  acid 
Turmeric  paper 
Zinc  (arsenic  free) 


INDEX  OF  AUTHORS  AND   TESTS 

PAGE 

Allen,  A.  H.,  Aniline  red  in  groxind  meats  15 

Glucose  in  honey 53 

Heavy  metals  in  fruits  and  fruit  products  ...  41 

in  meat 13 

in  vinegar 62 

Sulfuric  Acid  (distinguished  from  Sulfates)  in 

vinegar    60 

Tartar  in  vinegar 62 

Amthor,  Caramel  in  fruit  and  fruit  products 39 

Ashby,  Free  mineral  acids  in  vinegar 60 

Bechman,  Gelatin  in  jellies 41 

Bell  and  Carter,  Alum  in  flour    , 18 

Blyth,  Alum  in  bread 21 

Boettger,  Ergot  in  rye  flour 20 

Bornstein,  Saccharin  in  canned  vegetables 30 

Courley  and  Coremon,  Horseflesh  in  other  meats 16 

Delame,  Age  of  eggs   16 

Ebers,  Diseased  meat 16 

Frear,  Sulfuric  acid  in  vinegar 60 

Geisler,  Coal-tar  colors  in  butter    '. 7 

Girard  and  Dupre,  Acid  magenta  in  catsups  and  tomatoes  38 

Cochineal  in  catsups  and  tomatoes    ...  32 

Cochineal  in  canned  vegetables 34 

Gutzeit,  Arsenic  in  canned  fruits      42 

Halphen,  Cottonseed  oil  in  lard 64 

Hehner,  Formaldehyde  in  milk 4 

Henzold,  Gelatin  in  jellies    40 

Hess  and  Doolittle,  Process  or  renovated  butter  test  f or   . .  7 

Hess,  Foreign  resins  in  vanilla  extract 49 

Kammerer,  Sulfurous  acid  in  meat n 

75 


76  INDEX 

PAGE 

Kleeburg,  Wheat  in  rye  flour 20 

Klingler  and  Bujard,  Cochineal  carmine  in  meat 15 

Kraemer,  Corn  meal  in  wheat  flour 19 

Leach,  Caramel  in  milk    2 

Coiunarin  in  vanilla  extract 51 

Malic  acid  in  vinegar 61 

Salicylic  acid  in  milk   5 

Salicylic  acid  in  meat 12 

Lythgoe,  Coal-tar  colors  in  milk 3 

Marsh,  Arsenic  in  canned  fruits    41 

Martin,  Coloring  matter  in  butter 6 

Mobler,  Benzoic  acid  in  meat 12 

Benzoic  acid  in  canned  and  bottled  vegetables 31 

Benzoic  acid  in  fruit  and  fruit  products 37 

Mullikin  and  Scudder,  Methyl  alcohol  in  lemon  extract 46 

MuUikin  S.  P.,  Methyl  alcohol  in  lemon  extract    47 

Peter,  Benzoic  acid  in  canned  vegetables 31 

Richards,  Mrs.,  Alum  in  baking  powders    24 

Rimmington,  chicory  in  cofifee 70 

Schmidt,  Saccharin  in  canned  vegetables    30 

Smith,  chicory  in  coffee    71 

Sostegni  and  Carpentieri,  Coal-tar  dyes  in  canned  vegeta- 
bles    32 

Coal-tar  dyes  in  fruit  and  fruit  products  38 

Stoke,  Gelatin  in  milk 3 

Tocher,  sesame  oil  in  olive  oil 68 

Vanderplanken,  Alum  in  sour  bread 21 

Vogel,  Substituted  flours    19 

Wynther-Blyth,  alum  in  flour     18 

Wolff,  Tartaric  acid  (free  or  combined)  in  baking  powders  22 


INDEX 

PAGE 

Acid  magenta  in  fruit  and  fruit  products 38 

Agar  agar  in  fruit  and  fruit  products 41 

Alkali  in  vanilla  extract 49 

Allen,  A.  H.,  heavy  metals  in  fruit  and  fruit  products 41 

in  meat 13 

in  vinegar 62 

sulfuric  acid  in  vinegar 60 

tartar  in  vinegar 62 

test  of  coffee 69 

Alum  in  baking  powders 24 

in  bread 20 

in  floiu: 18 

in  pickles 34 

Aluminium  salts  in  cream  of  tartar    26 

Ammonia  in  cream  of  tartar 26 

Ammonium  salts  in  baking  powders 24 

Amthor,  caramel  in  fruit  and  fruit  products 39 

Aniline  red  in  meat 15 

Annatto  in  butter 6 

in  milk 2 

Apple  juice  in  jellies  made  from  small  fruits 39 

Arsenic  in  fruit  and  fruit  products 49 

Ashby,  free  mineral  adds  in  vinegar 61 

Bach,  test  of  olive  oil 60 

Baking  powders 22 

Adulterations  of 22 

Aliun 24 

Ammonium  salts 24 

G3^sum 24 

77 


78  INDEX 

PAGE 

Sulfates  (calcium,  etc.) 24 

Tartaric  add  (free) 23 

Tartaric  acid  (free  or  combined) 22 

Beechman,  gelatin  in  jellies 41 

Beef  stearin  in  lard 65 

Bell  and  Carter,  alum  in  flour 18 

Benzoic  acid  in  meat 12 

in  canned  vegetables 30 

in  fruit  and  fruit  products 37 

BIyth,  alum  in  bread 21 

Boettger,  ergot  in  rye  flour 20 

Borax  in  fish  and  oysters 15 

in  meats 11 

Boric  acid  in  fish  and  oysters 15 

in  meat 11 

in  mUk 5 

Bomstein,  saccharin  in  canned  vegetables 30 

Bread 20 

Adulterations  of 20 

Alimi 20 

Copper  sulfate 21 

Butter 6 

Adulterations  of 6 

Coloring  matter 6 

Annatto 6 

Coal-tar  colors 7 

Marigold 7 

Saffron 7 

Turmeric 7 

Cottonseed  oil 9 

Oleomargarine 8 

Process  or  renovated  butter 7 

Cane  sugar  in  honey 52 

Canned  and  bottled  vegetables 27 

Adulterations  of 27 

Alum  in  pickles 34 


INDEX  79 

PAGE 

Coal-tar  colors 32 

Cochineal 32 

Coloring  matter 32 

Copper  salts  in  green  pickles,  beans,  peas,  etc 33 

Turmeric  in  mixed  pickles 33 

Examination  of  can  or  box 34 

Heavy  metals  other  than  copper  (see  imder  meats) 13 

Preservatives 28 

Benzoic  add 30 

Formaldehyde .* . . .  8 

Saccharin 29 

Salicylic  acid 29 

Sulf urous  acid 29 

Soaked  vegetables,  peas,  beans,  and  com 33 

Caramel  in  fruit  and  fruit  products 39 

in  milk 2 

in  vanilla  extract 50 

in  vinegar 61 

Catechu  in  tea 72 

Cayenne  pepper  in  black  pepper 57 

in  mustard 56 

Cereal  products 18 

Chicory  in  coffee 70 

Citral  in  lemon  extract 45 

Citric  acid  in  lemon  extract 46 

Coal-tar  colors  in  butter 7 

in  canned  vegetables 32 

in  fruit  and  fruit  products 38 

in  lemon  extract 48 

in  milk 3 

in  vinegar 62 

Cochineal  carmine  in  canned  vegetables 32 

in  fruit  and  fruit  products 38 

in  meat 15 

Coffee 69 

Adulterations  of 69 


8o  INDEX 

VAGE 

Chicory 70 

Coloring  matter 69 

Imitation  coffee  beans 70 

Starch 70 

Coloring  matters: 

Acid  magenta  in  fruit  and  fruit  products 38 

Aniline  red  in  meat 15 

Aimatto  in  butter 6 

in  milk 2 

Caramel  in  fruit  and  fruit  products 39 

in  milk 2 

in  vanilla  extract $0 

in  vinegar 61 

Copper  salts  in  canned  vegetables 33 

Copper  sulfate  in  bread 21 

in  flour 19 

Cottonseed  oil  in  butter 9 

in  lard 64 

in  olive  oil 66 

Stearin  in  lard 64 

Coimiarin  in  vanilla  extract 51 

Courley  and  Coremon,  horseflesh  in  other  meats 16 

Cream  of  tartar 25 

Adulterations  of 25 

Aluminium  salts 26 

Ammonia 26 

Earthy  materials 26 

Tartaric  add  (free  or  combined) 25 

Djury  products i 

Ebers,  diseased  meat 16 

Eggs,  test  for  freshness 16 

Elaiden  test 66 

Exhausted  tea  leaves  in  tea 71 

Facing  in  tea 73 

Fats  and  oils 64 

Lard 64 


INDEX  8jt 

PAGE 

Adulterations  of 64 

Beef-stearin 65 

Cottonseed  oil 65 

stearin 64 

Olive  oil 65 

Adulterations  of 65 

Cottonseed  oil 66 

Peanut  oil 67 

Rape  oil 68 

Sesame  oil 68 

Fish,  preservative  in 15 

Flavoring  extracts 45 

Flour 18 

Adulterations  of 18 

Alum 18 

Copper  sulfate 19 

Substituted  flours 19 

Com  meal  in  wheat  flour 19 

Ergot  in  rye  flour 20 

Wheat  flour  in  rye  flour 20 

Flour  in  mustard 54 

Formaldehyde  in  canned  vegetables 28 

in  milk 4 

Frear,  sulfuric  add  in  vinegar 60 

Fruit  and  fruit  products 36 

Adulterations  of 36 

Agar  agar 41 

Apple  juice  in  jellies  made  from  small  fruits 39 

Arsenic 41 

Coloring  matter 38 

Add  magenta 38 

Caramel 39 

Coal-tar  dyes 38 

Cochineal 38 

Gelatin  in  jellies 40 

Heavy  metals 41 


82  INDEX 

PAGE 

Preservatives 36 

Benzoic  add 37 

Saccharin 37 

Salicylic  add 37 

Starch  in  jellies,  jams,  and  such  products 40 

Gelatin  in  honey 53 

in  jellies 40 

in  milk 3 

Geisler,  coal-tar  colors  in  butter 7 

Ginger  cake,  stannous  chlorid  in 18 

Girard   and   Dupre,   add   magenta   in   fruit  and   fruit  pro- 
ducts    38 

cochineal  in  catsups  and  tomatoes 32 

in  canned  vegetables 32 

Glucose  in  honey 53 

in  maple  syrup 53 

Gutzeit,  arsenic  in  canned  fruits 42 

Gypsum  in  baking  powders 24 

Heavy  metals  in  canned  vegetables 13 

in  fruit  and  fruit  products 41 

in  meat 13 

Hehner,  formaldehyde  in  mUk 4 

Henzold,  gelatin  in  jellies 40 

Hess  and  DooUttle,  test  for  process  butter 7 

Honey S* 

Adulterations  of 52 

Cane  sugar 52 

Commerdal  glucose 53 

Gelatin 53 

Horseflesh  in  sausage  and  mince-meat 16 

Hydrochloric  add  in  vinegar 60 

test  for  formaldehyde 4,  28 

Imitation  coffee  beans 70 

Kammerer,  sulf urous  acid  in  meat 11 

KJeeburg,  wheat  in  rye  flour 20 

Klingler  and  Bujard,  cochineal-carmine  in  meat 15 


INDEX  83 

PAGE 

Kraemer,  com  meal  in  wheat  flour 19 

Lard 64 

Adulterations  of 64 

Beef -stearin 65 

Cottonseed  oil 64 

stearin 64 

Leach,  caramel  in  milk 2 

malic  add  in  vinegar 61 

salicylic  acid  in  meat 12 

in  milk 5 

Lemon  extract 45 

Adulterations  of 45 

Citral 45 

Coloring  matter 48 

Coal-tar  dyes 48 

Turmeric 48 

Lemon  oil    45 

Methyl  alcohol 46 

Oil  of  citronella 46 

Tartaric  or  citric  add 46 

Lemon  oil  in  lemon  extract 45 

Lie  tea  in  tea 72 

Lythgoe,  coal-tar  colors  in  milk    3 

Malic  add  in  vinegar    61 

Maple  syrup 53 

Adulterations  of S3 

Glucose 53 

Marigold  in  butter 7 

Marsh,  arsenic  in  fruit  products 41 

Martin,  coloring  matter  in  butter 6 

Martins  yellow  in  mustard $$ 

Meats 10 

Adulterations  of 10 

Canned 13 

Coloring  matter  (see  under  sausages,  etc.) 15 

Heavy  metals 13 


84  INDEX 

PAGE 

Preservatives  (same  tests  as  under  smoked  and  fresh 

meat) 13 

Coloring  matter 15 

Aniline  red  and  cochineal-carmine  in  sausage,  chopped 

meat  preparations,  and  corned  meat      15 

Diseased  meat 16 

Fresh  and  smoked 10 

Preservatives    lo 

Benzoic  acid 12 

Boric  add 11 

Potassium  nitrate 10 

Salicylic  add 12 

Sulfurous  add 11 

Fish,  salt,  dried,  and  oysters 15 

Preservatives    15 

Borax  (same  as  under  fresh  meat) 15 

Boric  acid  (same  as  under  fresh  meat) 15 

Horseflesh  in  sausage  and  mince-meat 16 

Starch  in  sausage,  deviled  meat,  and  similar  products. . .  15 

Metallic  impurities  in  vinegar 62 

Methyl  alcohol  in  lemon  extract • 46 

Mineral  adds  in  vinegar 59 

Milk I 

Adulterations  of i 

Coloring  matter z 

Annatto 2 

Caramel 2 

Coal-tar  dyes 3 

Gelatin 3 

Preservatives 4 

Boric  add 5 

Formaldehyde 4 

SaUcylic  add S 

Starch 3 

Mohler,  benzoic  add  in  meat 12 

in  fruit  and  fruit  products 73 


INDEX  8s 

PAGE 

Mustard 54 

Adulterations  of 54 

Cayenne  pepper 56 

Coloring  matter 54 

Martius  yellow  or  analogous  cx)al-tar  dyes 55 

Turmeric 55 

Flour. 54 

Oil  of  dtronella  in  lemon  extract 46 

Oleomargarine  in  butter 8 

Olive  oil 65 

Adulterations  of 65 

Cottonseed  oil 66 

Peanut  oil 67 

Rape  oil 68 

Sesame  oil 68 

Olive  stones  in  pepper 56 

Oysters,  preservatives  in 15 

Peanut  oil  in  olive  oil 67 

Pepper  (common) 56 

Adulterations  of 56 

Cayenne  pepper 56 

Ground  olive  stones 56 

Peter,  benzoic  acid  in  canned  vegetables 31 

Pontet,  general  test  of  olive  oil 66 

Potassium  nitrate  in  meat 10 

Preservatives: 

Benzoic  acid  in  canned  vegetables 30 

in  fruit  and  fruit  products 37 

in  meat 12 

Boric  add  in  fish  and  oysters iS 

in  meat 11 

in  milk      5 

Formaldehyde  in  canned  vegetables 28 

in  milk 4 

Potassivun  nitrate  in  meat 10 

Saccharin  in  canned  vegetables 20 

in  fruit  and  fruit  products 37 


86  INDEX 

PAGE 

Salicylic  add  in  canned  vegetables 29 

in  fruit  and  fruit  products 37 

in  meat 12 

in  milk 5 

Sulfites  in  canned  vegetables 20 

Sulf urous  acid  in  canned  vegetables 29 

Process  or  renovated  butter 7 

Rape  oil  in  olive  oil 68 

Resins,  foreign,  in  vanilla  extract 40 

Richards,  Mrs.,  alum  in  baking  powders 24 

Rimmington,  chicory  in  coffee 70 

Saccharin  in  canned  vegetables 29 

in  fruit  and  fruit  products 37 

Saffron  in  butter 7 

Salicylic  add  in  canned  vegetables 29 

in  fruit  and  fruit  products 37 

in  meat 12 

in  milk S 

Schmidt,  Albert,  chicory  in  coffee 71 

Schmidt,  saccharin  in  canned  vegetables 30 

Soaked  vegetables 33 

Sostegni  and  Carpentieri,  coal-tar  dyes  in  canned  vegetables. .  32 

Spices  in  vinegar 62 

Stoke,  gelatin  in  milk 3 

Substituted  flours 19 

Com  meal  in  wheat 19 

General  test  for 19 

Wheat  flour  in  rye 20 

Sulfates  in  baking  powders 24 

Sulfuric  add  in  vinegar 60 

Sulfurous  add  in  meat 11 

Stannous  chlorid  in  ginger  cake 18 

Starch  in  fruit  and  fruit  products 4° 

in  milk 3 

Tannin  in  vanilla  extracts 5° 

Tartar  in  vinegar 62 


INDEX  87 

PAGE 

Tartaric  add  in  baking  powders 22,  23 

in  cream  of  tartar 25 

in  lemon  extract 46 

in  wine  vinegar 63 

Tea 71 

Adulterations  of 71 

Catechu 72 

Exhausted  tea  leaves 71 

Facing 72 

Foreign  leaves 71 

Lie  tea 72 

Tocher,  sesame  oil  in  olive  oil 68 

Turmeric  in  butter 7 

in  lemon  extract 48 

in  mixed  pickles 33 

in  mustard 55 

Vanderplanken,  alum  in  sour  bread 21 

Vanilla  extract 48 

Adulterations  of 48 

Alkali 49 

Caramel 50 

Coumarin 51 

Foreign  resins 49 

Tannin 50 

Vinegar 58 

Adulterations  of 58 

Coloring  matter 61 

Caramel 61 

Coal-tar  colors  in  wine  vinegar 62 

Glucose 63 

Malic  add 61 

Metallic  impurities    62 

Mineral  adds  (free) 59 

Hydrochloric  add 60 

Sulfuric  add 60 

Spices 63 


88  INDEX 

PAGE 

Tartar  in  wine  vinegar 62 

Tartaric  acid  (free)  in  wine  vinegar 63 

Vogel,  substituted  flours 19 

Wynther,  Blyth,  alum  in  flour 18 

Wolff,  tartaric  add  free  or  combined  in  baking  powders 22 


LITERATURE    OF   THE 
CHEMICAL    INDUSTRIES 


On  our  shelves  is  the  most  complete  stock  of 
technical,  industrial,  engineering  and  scientific 
books  in  the  United  States,  The  technical  liter- 
ature of  every  trade  is  well  represented,  as  is 
also  the  literature  relating  to  the  various  sciences, 
both  the  books  useful  for  reference  as  well  as 
those  fitted  for  students'  use  as  textbooks. 

A  large  number  of  these  we  publish  and  for  an 
ever  increasing  number  we  are  the  sole  agents. 

ALL  INQUIRIES  MADE  OF  US  ARE  CHEER- 
FULLY AND  CAREFULLY  ANSWERED 
AND  COMPLETE  CATALOGS  AS  WELL  AS 
SPECIAL  LISTS  SENT   FREE  ON  REQUEST 


D.  VAN  NOSTRAND   COMPANY 

Publishers  and  Booksellers 
8  WARREN  STREET  NEW  YORK 


3 


THE  LIBRARY 
UNIVERSITY  OF  CALIFORNIA 

Santa  Barbara 


THIS  BOOK  IS  DUE  ON  THE  LAST  DATE 
STAMPED  BELOW. 


^,,^L  LiBR^R''  '"'^S'r'.Tuii 


000  577  990     5 


